"use strict"; const {Fragment: _Fragment, jsx: _jsx, jsxs: _jsxs} = arguments[0]; const {useMDXComponents: _provideComponents} = arguments[0]; function _createMdxContent(props) { const _components = { code: "code", h1: "h1", h2: "h2", h3: "h3", hr: "hr", li: "li", ol: "ol", p: "p", pre: "pre", span: "span", strong: "strong", ul: "ul", ..._provideComponents(), ...props.components }; return _jsxs(_Fragment, { children: [_jsx(_components.h1, { children: "Instructions: Cleanup and Memory Management" }), "\n", _jsx(_components.p, { children: "Follow these step-by-step instructions to build a timer management component that demonstrates professional cleanup functions and memory management. This exercise will reinforce the cleanup concepts you learned in the lesson and guide you through creating a reliable timer system that prevents memory leaks." }), "\n", _jsx(_components.h2, { children: "Concept Reinforcement" }), "\n", _jsx(_components.p, { children: "Before we start coding, let's review the key React concepts you'll be applying in this exercise:" }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Effect Cleanup Functions" }), ": You'll use cleanup functions returned from useEffect to properly cancel timers when components unmount or when timer configurations change. This prevents memory leaks and ensures optimal application performance."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Memory Management" }), ": You'll implement professional memory management patterns by tracking timer IDs and systematically cleaning them up. This is the same approach used by real-time dashboards, gaming applications, and productivity tools."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Multiple Timer Coordination" }), ": You'll manage multiple independent timers, each with their own lifecycle and cleanup requirements. This demonstrates how professional React applications coordinate multiple resources efficiently."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Resource Lifecycle Management" }), ": You'll see how React's component lifecycle integrates with resource management - timers are created when components mount and cleaned up when components unmount or when timer states change."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Professional Cleanup Patterns" }), ": You'll implement the same cleanup techniques used by applications like Slack (typing indicators), Spotify (playback timers), and productivity apps (work session timers)."] }), "\n", _jsx(_components.h2, { children: "The Challenge" }), "\n", _jsx(_components.p, { children: "Create a timer management application that demonstrates cleanup function mastery:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "Multiple independent timers that can be created, started, stopped, and removed" }), "\n", _jsx(_components.li, { children: "Proper cleanup functions that prevent memory leaks when timers are removed" }), "\n", _jsx(_components.li, { children: "Visual demonstration of cleanup effectiveness with timer status tracking" }), "\n", _jsx(_components.li, { children: "Professional timer interface with start/stop/remove controls" }), "\n", _jsx(_components.li, { children: "Memory management monitoring to show cleanup benefits" }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Success Criteria:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "✅ Component uses useEffect with proper cleanup functions for timer management" }), "\n", _jsx(_components.li, { children: "✅ Multiple timers can run independently without interfering with each other" }), "\n", _jsx(_components.li, { children: "✅ Cleanup functions properly cancel timers when components unmount or timers are removed" }), "\n", _jsx(_components.li, { children: "✅ No React warnings about state updates on unmounted components" }), "\n", _jsx(_components.li, { children: "✅ Timer interface provides professional start/stop/remove controls" }), "\n", _jsx(_components.li, { children: "✅ Components are organized in separate files with proper imports" }), "\n", _jsx(_components.li, { children: "✅ Visual demonstration of memory management and cleanup effectiveness" }), "\n"] }), "\n", _jsx(_components.h2, { children: "Independent Learning Opportunity" }), "\n", _jsx(_components.p, { children: "Before looking at the step-by-step guide below, try building this timer management component yourself! Use these React concepts you've learned:" }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "React Concepts to Use:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "Functional components with JSX and proper file organization" }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "useState" }), " hook for managing timer states, active timers, and timer configurations"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "useEffect" }), " hook with cleanup functions for timer lifecycle management"] }), "\n", _jsxs(_components.li, { children: ["Effect cleanup with ", _jsx(_components.code, { children: "clearInterval" }), " to cancel timers and prevent memory leaks"] }), "\n", _jsx(_components.li, { children: "Component composition with separate Timer components" }), "\n", _jsx(_components.li, { children: "Event handling for timer controls (start, stop, remove)" }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Conceptual Hints:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsx(_components.li, { children: "Think about what data needs to change over time (timer values, active states, timer list)" }), "\n", _jsx(_components.li, { children: "Consider what side effects you need to perform (creating and managing intervals)" }), "\n", _jsx(_components.li, { children: "Remember that useEffect cleanup functions run when components unmount or dependencies change" }), "\n", _jsx(_components.li, { children: "Use the cleanup function to cancel timers with clearInterval" }), "\n", _jsx(_components.li, { children: "Each timer should have its own unique ID for proper tracking and cleanup" }), "\n", _jsx(_components.li, { children: "Multiple timers should be managed independently with their own state and effects" }), "\n"] }), "\n", _jsx(_components.p, { children: "Try building it yourself first - it's okay if you get stuck! The step-by-step guide below will help you understand each React concept as you implement it." }), "\n", _jsx(_components.hr, {}), "\n", _jsx(_components.h2, { children: "Step-by-Step React Implementation Guide" }), "\n", _jsx(_components.p, { children: "If you need help or want to understand each React concept in detail, follow these steps:" }), "\n", _jsx(_components.h3, { children: "Step 1: Create the Timer Component File" }), "\n", _jsxs(_components.p, { children: ["Create a new file called ", _jsx(_components.code, { children: "Timer.js" }), " and set up a basic React component for individual timer management. This demonstrates React's component-based architecture and separation of concerns."] }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsx(_components.span, { className: "token imports", children: _jsx(_components.span, { className: "token maybe-class-name", children: "React" }) }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "2", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "3", children: [_jsx(_components.span, { className: "token keyword", children: "function" }), " ", _jsx(_components.span, { className: "token function", children: _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }) }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token parameter", children: [_jsx(_components.span, { className: "token punctuation", children: "{" }), " id", _jsx(_components.span, { className: "token punctuation", children: "," }), " onRemove ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "4", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsx(_components.span, { 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children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "div"] }), " ", _jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "timer-header", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "7", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "h3"] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "Timer #" }), _jsx(_components.span, { className: "token punctuation", children: "{" }), "id", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "8", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), 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}), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "11", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "12", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "div"] }), " ", _jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "timer-display", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "00:00" }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", 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maybe-class-name", children: "Timer" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "function Timer({ id, onRemove })" }), " creates a functional component that accepts props for timer identification and removal"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "onClick={() => onRemove(id)}" }), " creates an event handler that calls the parent's remove function with this timer's ID"] }), "\n", _jsx(_components.li, { children: "The JSX structure creates a professional timer interface with display and controls" }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "export default Timer" }), " makes this component available for import in other files"] }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates component composition and props - creating reusable components that accept configuration through props and communicate with parent components through callback functions."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " to see your basic timer component structure! Notice the professional styling and clean interface layout."] }), "\n", _jsx(_components.h3, { children: "Step 2: Add Timer State and Basic Functionality" }), "\n", _jsx(_components.p, { children: "Add state management to the Timer component for tracking time, running status, and timer controls. This creates the foundation for timer functionality." }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsxs(_components.span, { className: "token imports", children: [_jsx(_components.span, { className: "token maybe-class-name", children: "React" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), " useState ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", 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"token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "52", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "53", children: [_jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "54", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "55", children: [_jsx(_components.span, { className: "token keyword module", children: "export" }), " ", _jsx(_components.span, { className: "token keyword module", children: "default" }), " ", _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [seconds, setSeconds] = useState(0)" }), " tracks the elapsed time for this timer"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [isRunning, setIsRunning] = useState(false)" }), " tracks whether the timer is currently active"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const handleStart = () => { setIsRunning(true) }" }), " creates an event handler to start the timer"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const formatTime = (totalSeconds) => { ... }" }), " creates a helper function to display time in MM:SS format"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "disabled={isRunning}" }), " and ", _jsx(_components.code, { children: "disabled={!isRunning}" }), " prevent inappropriate button clicks"] }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates React state management for component-specific data and controlled UI elements that respond to state changes."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " to see your timer component with state management! Notice how the buttons enable/disable based on timer status and the display shows formatted time."] }), "\n", _jsx(_components.h3, { children: "Step 3: Add useEffect for Timer Interval Management" }), "\n", _jsx(_components.p, { children: "Import and use the useEffect hook to create the timer interval with proper cleanup. This is where the memory management magic happens!" }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsxs(_components.span, { className: "token imports", children: [_jsx(_components.span, { className: "token maybe-class-name", children: "React" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), " useState", _jsx(_components.span, { className: "token punctuation", children: "," }), " useEffect ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "2", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "3", children: [_jsx(_components.span, { className: "token keyword", children: "function" }), " ", _jsx(_components.span, { className: "token function", children: _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }) }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token parameter", children: [_jsx(_components.span, { className: "token punctuation", children: "{" }), " id", _jsx(_components.span, { className: "token punctuation", children: "," }), " onRemove ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "4", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "seconds", _jsx(_components.span, { className: "token punctuation", children: "," }), " setSeconds", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "0" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "5", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: "," }), " setIsRunning", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token boolean", children: "false" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "6", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "7", children: [" ", _jsx(_components.span, { className: "token function", children: "useEffect" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "8", children: [" ", _jsx(_components.span, { className: "token keyword", children: "let" }), " intervalId ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token keyword null nil", children: "null" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "9", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "10", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "11", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Create interval when timer is running" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "12", children: [" intervalId ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "setInterval" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "13", children: [" ", _jsx(_components.span, { className: "token function", children: "setSeconds" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prevSeconds" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " prevSeconds ", _jsx(_components.span, { className: "token operator", children: "+" }), " ", _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "14", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token number", children: "1000" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "15", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "16", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "17", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Cleanup function cancels interval" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "18", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "19", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "intervalId", _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "20", children: [" ", _jsx(_components.span, { className: "token function", children: "clearInterval" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), "intervalId", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "21", children: [" ", _jsx(_components.span, { className: "token console class-name", children: "console" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "log" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token template-string", children: [_jsx(_components.span, { className: "token template-punctuation string", children: "`" }), _jsx(_components.span, { className: "token string", children: "Timer " }), _jsxs(_components.span, { className: "token interpolation", children: [_jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "${" }), "id", _jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "}" })] }), _jsx(_components.span, { className: "token string", children: " interval cleaned up" }), _jsx(_components.span, { className: "token template-punctuation string", children: "`" })] }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "22", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "23", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "24", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: "," }), " id", _jsx(_components.span, { className: "token punctuation", children: "]" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), " ", _jsx(_components.span, { className: "token comment", children: "// Effect runs when isRunning changes" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "25", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "26", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "handleStart" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "27", children: [" ", _jsx(_components.span, { className: "token function", children: "setIsRunning" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token boolean", children: "true" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "28", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "29", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "30", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "handleStop" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "31", children: [" ", _jsx(_components.span, { className: "token function", children: "setIsRunning" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token boolean", children: "false" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "32", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "33", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "34", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "formatTime" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token parameter", children: "totalSeconds" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "35", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " minutes ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token known-class-name class-name", children: "Math" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "floor" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), "totalSeconds ", _jsx(_components.span, { className: "token operator", children: "/" }), " ", _jsx(_components.span, { className: "token number", children: "60" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "36", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " seconds ", _jsx(_components.span, { className: "token operator", children: "=" }), " totalSeconds ", _jsx(_components.span, { className: "token operator", children: "%" }), " ", _jsx(_components.span, { className: "token number", children: "60" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "37", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsxs(_components.span, { className: "token template-string", children: [_jsx(_components.span, { className: "token template-punctuation string", children: "`" }), _jsxs(_components.span, { className: "token interpolation", children: [_jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "${" }), "minutes", _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "toString" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "padStart" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "2" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token string", children: "'0'" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "}" })] }), _jsx(_components.span, { className: "token string", children: ":" }), _jsxs(_components.span, { className: "token interpolation", children: [_jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "${" }), "seconds\n"] })] })] }), _jsx(_components.span, { className: "code-line line-number", line: "38", children: _jsx(_components.span, { className: "token template-string", children: _jsxs(_components.span, { className: "token interpolation", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "toString" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), "\n"] }) }) }), _jsxs(_components.span, { className: "code-line line-number", line: "39", children: [_jsxs(_components.span, { className: "token template-string", children: [_jsxs(_components.span, { className: "token interpolation", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "padStart" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "2" 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[_jsx(_components.span, { className: "token punctuation", children: "<" }), "div"] }), " ", _jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "empty-state", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "54", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "p"] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "No timers created yet." }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "55", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "p"] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "Click \"Add New Timer\" to get started!" }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "56", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "57", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "58", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "59", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "60", children: [_jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "61", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "62", children: [_jsx(_components.span, { className: "token keyword module", children: "export" }), " ", _jsx(_components.span, { className: "token keyword module", children: "default" }), " ", _jsx(_components.span, { className: "token maybe-class-name", children: "TimerManager" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [timers, setTimers] = useState([])" }), " manages an array of timer objects"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [nextId, setNextId] = useState(1)" }), " tracks the next unique ID for new timers"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const addTimer = () => { ... }" }), " creates a new timer object and adds it to the array"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const removeTimer = (timerId) => { ... }" }), " removes a timer from the array by filtering"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "{timers.map(timer => )}" }), " renders a Timer component for each timer in the array"] }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates array state management and component composition - managing a dynamic list of components where each component has its own state and cleanup requirements."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " to see your timer management interface! Try adding multiple timers and notice how each one operates independently."] }), "\n", _jsx(_components.h3, { children: "Step 5: Add Memory Management Monitoring" }), "\n", _jsx(_components.p, { children: "Add monitoring features to visualize cleanup effectiveness and demonstrate memory management benefits. This shows the real-world impact of proper cleanup functions." }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsxs(_components.span, { className: "token imports", children: [_jsx(_components.span, { className: "token maybe-class-name", children: "React" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), " useState", _jsx(_components.span, { className: "token punctuation", children: "," }), " useEffect ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "2", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsx(_components.span, { className: "token imports", children: _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }) }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'./Timer'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "3", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "4", children: [_jsx(_components.span, { className: "token keyword", children: "function" }), " ", _jsx(_components.span, { className: "token function", children: _jsx(_components.span, { className: "token maybe-class-name", children: "TimerManager" }) }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "5", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "timers", _jsx(_components.span, { className: "token punctuation", children: "," }), " setTimers", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "[" }), _jsx(_components.span, { className: "token punctuation", children: "]" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "6", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "nextId", _jsx(_components.span, { className: "token punctuation", children: "," }), " setNextId", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "7", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "totalTimersCreated", _jsx(_components.span, { className: "token punctuation", children: "," }), " setTotalTimersCreated", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "0" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "8", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "cleanupCount", _jsx(_components.span, { className: "token punctuation", children: "," }), " setCleanupCount", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "0" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "9", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "10", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Effect to track cleanup events from child components" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "11", children: [" ", _jsx(_components.span, { className: "token function", children: "useEffect" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "12", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "handleCleanupEvent" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token parameter", children: "event" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "13", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "event", _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token property-access", children: "detail" }), " ", _jsx(_components.span, { className: "token operator", children: "&&" }), " event", _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token property-access", children: "detail" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token property-access", children: "type" }), " ", _jsx(_components.span, { className: "token operator", children: "===" }), " ", _jsx(_components.span, { className: "token string", children: "'timer-cleanup'" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "14", children: [" ", _jsx(_components.span, { className: "token function", children: "setCleanupCount" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prev" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " prev ", _jsx(_components.span, { className: "token operator", children: "+" }), " ", _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "15", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "16", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "17", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "18", children: [" ", _jsx(_components.span, { className: "token dom variable", children: "window" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "addEventListener" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token string", children: "'timer-cleanup'" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " handleCleanupEvent", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "19", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "20", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "21", children: [" ", _jsx(_components.span, { className: "token dom variable", children: "window" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "removeEventListener" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token string", children: "'timer-cleanup'" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " handleCleanupEvent", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "22", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "23", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), _jsx(_components.span, { className: "token punctuation", children: "]" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "24", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "25", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "addTimer" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "26", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " newTimer ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "27", children: [" ", _jsx(_components.span, { className: "token literal-property property", children: "id" }), _jsx(_components.span, { className: "token operator", children: ":" }), " nextId", _jsx(_components.span, { className: "token punctuation", children: "," }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "28", children: [" ", _jsx(_components.span, { className: "token literal-property property", children: "createdAt" }), _jsx(_components.span, { className: "token operator", children: ":" }), " ", _jsx(_components.span, { className: "token keyword", children: "new" }), " ", _jsx(_components.span, { className: "token class-name", children: "Date" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "toLocaleTimeString" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: "," }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "29", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "30", children: [" ", _jsx(_components.span, { className: "token function", children: "setTimers" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prevTimers" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), _jsx(_components.span, { className: "token spread operator", children: "..." }), "prevTimers", _jsx(_components.span, { className: "token punctuation", children: "," }), " newTimer", _jsx(_components.span, { className: "token punctuation", children: "]" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "31", children: [" ", _jsx(_components.span, { className: "token function", children: "setNextId" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prevId" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " prevId ", _jsx(_components.span, { className: "token operator", children: "+" }), " ", _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "32", children: [" ", _jsx(_components.span, { className: "token function", children: "setTotalTimersCreated" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prev" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " prev ", _jsx(_components.span, { className: "token operator", children: "+" }), " ", _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "33", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "34", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "35", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token function-variable function", children: "removeTimer" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token parameter", children: "timerId" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "36", 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punctuation", children: "<" }), "p"] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "Click \"Add New Timer\" to get started!" }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "122", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "p"] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsx(_components.span, { className: "code-line line-number", line: "123", children: _jsx(_components.span, { className: "token plain-text", children: " Watch the cleanup statistics as you create and remove\n" }) }), _jsx(_components.span, { className: "code-line line-number", line: "124", children: _jsx(_components.span, { className: "token plain-text", children: " timers!\n" }) }), _jsxs(_components.span, { className: "code-line line-number", line: "125", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "126", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "127", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "128", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "129", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "130", children: [_jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "131", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "132", children: [_jsx(_components.span, { className: "token keyword module", children: "export" }), " ", _jsx(_components.span, { className: "token keyword module", children: "default" }), " ", _jsx(_components.span, { className: "token maybe-class-name", children: "TimerManager" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [totalTimersCreated, setTotalTimersCreated] = useState(0)" }), " tracks total timers for memory monitoring"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "const [cleanupCount, setCleanupCount] = useState(0)" }), " tracks how many cleanup operations have occurred"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "useEffect(() => { ... }, [])" }), " sets up event listener for cleanup events from child components"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "window.addEventListener('timer-cleanup', handleCleanupEvent)" }), " listens for cleanup events"] }), "\n", _jsx(_components.li, { children: "The memory monitor section displays real-time statistics about timer management and cleanup effectiveness" }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates parent-child component communication and event-driven architecture for tracking cleanup operations across multiple components."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " and try adding multiple timers! Watch the memory management statistics update as you create and remove timers."] }), "\n", _jsx(_components.h3, { children: "Step 6: Update Timer Component with Cleanup Tracking" }), "\n", _jsx(_components.p, { children: "Update the Timer component to include proper cleanup functions and cleanup event reporting. This demonstrates professional memory management patterns." }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsxs(_components.span, { className: "token imports", children: [_jsx(_components.span, { className: "token maybe-class-name", children: "React" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), " useState", _jsx(_components.span, { className: "token punctuation", children: "," }), " useEffect ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "2", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "3", children: [_jsx(_components.span, { className: "token keyword", children: "function" }), " ", _jsx(_components.span, { className: "token function", children: _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }) }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token parameter", children: [_jsx(_components.span, { className: "token punctuation", children: "{" }), " id", _jsx(_components.span, { className: "token punctuation", children: "," }), " onRemove", _jsx(_components.span, { className: "token punctuation", children: "," }), " onCleanup ", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "4", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "seconds", _jsx(_components.span, { className: "token punctuation", children: "," }), " setSeconds", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token number", children: "0" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "5", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: "," }), " setIsRunning", _jsx(_components.span, { className: "token punctuation", children: "]" }), " ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "useState" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token boolean", children: "false" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "6", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "7", children: [" ", _jsx(_components.span, { className: "token function", children: "useEffect" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "8", children: [" ", _jsx(_components.span, { className: "token keyword", children: "let" }), " intervalId ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token keyword null nil", children: "null" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "9", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "10", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "11", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Create interval when timer is running" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "12", children: [" intervalId ", _jsx(_components.span, { className: "token operator", children: "=" }), " ", _jsx(_components.span, { className: "token function", children: "setInterval" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "13", children: [" ", _jsx(_components.span, { className: "token function", children: "setSeconds" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token parameter", children: "prevSeconds" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " prevSeconds ", _jsx(_components.span, { className: "token operator", children: "+" }), " ", _jsx(_components.span, { className: "token number", children: "1" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "14", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token number", children: "1000" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "15", children: [" ", _jsx(_components.span, { className: "token console class-name", children: "console" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "log" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token template-string", children: [_jsx(_components.span, { className: "token template-punctuation string", children: "`" }), _jsx(_components.span, { className: "token string", children: "Timer " }), _jsxs(_components.span, { className: "token interpolation", children: [_jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "${" }), "id", _jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "}" })] }), _jsx(_components.span, { className: "token string", children: " started with interval ID:" }), _jsx(_components.span, { className: "token template-punctuation string", children: "`" })] }), _jsx(_components.span, { className: "token punctuation", children: "," }), " intervalId", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "16", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "17", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "18", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Cleanup function cancels interval" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "19", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token arrow operator", children: "=>" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "20", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "intervalId", _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "21", children: [" ", _jsx(_components.span, { className: "token function", children: "clearInterval" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), "intervalId", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "22", children: [" ", _jsx(_components.span, { className: "token console class-name", children: "console" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "log" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsxs(_components.span, { className: "token template-string", children: [_jsx(_components.span, { className: "token template-punctuation string", children: "`" }), _jsx(_components.span, { className: "token string", children: "Timer " }), _jsxs(_components.span, { className: "token interpolation", children: [_jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "${" }), "id", _jsx(_components.span, { className: "token interpolation-punctuation punctuation", children: "}" })] }), _jsx(_components.span, { className: "token string", children: " interval cleaned up" }), _jsx(_components.span, { className: "token template-punctuation string", children: "`" })] }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "23", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "24", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Dispatch cleanup event for monitoring" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "25", children: [" ", _jsx(_components.span, { className: "token dom variable", children: "window" }), _jsx(_components.span, { className: "token punctuation", children: "." }), _jsx(_components.span, { className: "token method function property-access", children: "dispatchEvent" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "26", children: [" ", _jsx(_components.span, { className: "token keyword", children: "new" }), " ", _jsx(_components.span, { className: "token class-name", children: "CustomEvent" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token string", children: "'timer-cleanup'" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "27", children: [" ", _jsx(_components.span, { className: "token literal-property property", children: "detail" }), _jsx(_components.span, { className: "token operator", children: ":" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), " ", _jsx(_components.span, { className: "token literal-property property", children: "type" }), _jsx(_components.span, { className: "token operator", children: ":" }), " ", _jsx(_components.span, { className: "token string", children: "'timer-cleanup'" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token literal-property property", children: "timerId" }), _jsx(_components.span, { className: "token operator", children: ":" }), " id ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "28", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "29", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "30", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "31", children: [" ", _jsx(_components.span, { className: "token comment", children: "// Call parent cleanup callback" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "32", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "if" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "onCleanup", _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "33", children: [" ", _jsx(_components.span, { className: "token function", children: "onCleanup" }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "34", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "35", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "36", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "37", children: [" ", _jsx(_components.span, { className: "token punctuation", children: "}" }), _jsx(_components.span, { className: "token punctuation", children: "," }), " ", _jsx(_components.span, { className: "token punctuation", children: "[" }), "isRunning", _jsx(_components.span, { className: "token punctuation", children: "," }), " id", _jsx(_components.span, { className: "token punctuation", children: "," }), " onCleanup", _jsx(_components.span, { className: "token punctuation", children: "]" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), " ", _jsx(_components.span, { className: "token comment", children: "// Effect runs when isRunning changes" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "38", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "39", children: [" ", _jsx(_components.span, { className: "token keyword", children: "const" }), " ", _jsx(_components.span, { className: "token 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_jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "control-button stop", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), "\n"] }) }), _jsxs(_components.span, { className: "code-line line-number", line: "84", children: [_jsxs(_components.span, { className: "token tag", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsx(_components.span, { className: "code-line line-number", line: "85", children: _jsx(_components.span, { className: "token plain-text", children: " Stop\n" }) }), _jsxs(_components.span, { className: "code-line line-number", line: "86", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "87", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "button"] }), " ", _jsx(_components.span, { className: "token attr-name", children: "onClick" }), _jsxs(_components.span, { className: "token script language-javascript", children: [_jsx(_components.span, { className: "token script-punctuation punctuation", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "{" }), "handleReset", _jsx(_components.span, { className: "token punctuation", children: "}" })] }), " ", _jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "control-button reset", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsx(_components.span, { className: "code-line line-number", line: "88", children: _jsx(_components.span, { className: "token plain-text", children: " Reset\n" }) }), _jsxs(_components.span, { className: "code-line line-number", line: "89", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "90", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "91", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "92", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "93", children: [_jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "94", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "95", children: [_jsx(_components.span, { className: "token keyword module", children: "export" }), " ", _jsx(_components.span, { className: "token keyword module", children: "default" }), " ", _jsx(_components.span, { className: "token maybe-class-name", children: "Timer" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "{ useEffect }" }), " imports the useEffect hook for side effect and cleanup management"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "let intervalId = null" }), " declares a variable to track the interval ID for cleanup"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "intervalId = setInterval(() => { ... }, 1000)" }), " creates the timer interval when running"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "return () => { clearInterval(intervalId) }" }), " is the cleanup function that prevents memory leaks"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "window.dispatchEvent(new CustomEvent('timer-cleanup', ...))" }), " reports cleanup events for monitoring"] }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates useEffect cleanup functions for preventing memory leaks - intervals are created when needed and automatically cleaned up when timers stop or components unmount."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " and try starting/stopping timers! Watch the console for cleanup messages and see the cleanup statistics update in real-time."] }), "\n", _jsx(_components.h3, { children: "Step 7: Update the App Component" }), "\n", _jsxs(_components.p, { children: ["Now update your ", _jsx(_components.code, { children: "App.js" }), " file to import and use your TimerManager component. This demonstrates React's component composition and import/export system."] }), "\n", _jsx(_components.pre, { className: "language-jsx", children: _jsxs(_components.code, { className: "language-jsx code-highlight", children: [_jsxs(_components.span, { className: "code-line line-number", line: "1", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsx(_components.span, { className: "token imports", children: _jsx(_components.span, { className: "token maybe-class-name", children: "React" }) }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'react'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "2", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsx(_components.span, { className: "token imports", children: _jsx(_components.span, { className: "token maybe-class-name", children: "TimerManager" }) }), " ", _jsx(_components.span, { className: "token keyword module", children: "from" }), " ", _jsx(_components.span, { className: "token string", children: "'./TimerManager'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "3", children: [_jsx(_components.span, { className: "token keyword module", children: "import" }), " ", _jsx(_components.span, { className: "token string", children: "'./styles.css'" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "4", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "5", children: [_jsx(_components.span, { className: "token keyword", children: "function" }), " ", _jsx(_components.span, { className: "token function", children: _jsx(_components.span, { className: "token maybe-class-name", children: "App" }) }), _jsx(_components.span, { className: "token punctuation", children: "(" }), _jsx(_components.span, { className: "token punctuation", children: ")" }), " ", _jsx(_components.span, { className: "token punctuation", children: "{" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "6", children: [" ", _jsx(_components.span, { className: "token keyword control-flow", children: "return" }), " ", _jsx(_components.span, { className: "token punctuation", children: "(" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "7", children: [" ", _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), "div"] }), " ", _jsx(_components.span, { className: "token attr-name", children: "className" }), _jsxs(_components.span, { className: "token attr-value", children: [_jsx(_components.span, { className: "token punctuation attr-equals", children: "=" }), _jsx(_components.span, { className: "token punctuation", children: "\"" }), "App", _jsx(_components.span, { className: "token punctuation", children: "\"" })] }), _jsx(_components.span, { className: "token punctuation", children: ">" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "8", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "<" }), _jsx(_components.span, { className: "token class-name", children: "TimerManager" })] }), " ", _jsx(_components.span, { className: "token punctuation", children: "/>" })] }), _jsx(_components.span, { className: "token plain-text", children: "\n" })] }), _jsxs(_components.span, { className: "code-line line-number", line: "9", children: [_jsx(_components.span, { className: "token plain-text", children: " " }), _jsxs(_components.span, { className: "token tag", children: [_jsxs(_components.span, { className: "token tag", children: [_jsx(_components.span, { className: "token punctuation", children: "" })] }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "10", children: [" ", _jsx(_components.span, { className: "token punctuation", children: ")" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] }), _jsxs(_components.span, { className: "code-line line-number", line: "11", children: [_jsx(_components.span, { className: "token punctuation", children: "}" }), "\n"] }), _jsx(_components.span, { className: "code-line line-number", line: "12", children: "\n" }), _jsxs(_components.span, { className: "code-line line-number", line: "13", children: [_jsx(_components.span, { className: "token keyword module", children: "export" }), " ", _jsx(_components.span, { className: "token keyword module", children: "default" }), " ", _jsx(_components.span, { className: "token maybe-class-name", children: "App" }), _jsx(_components.span, { className: "token punctuation", children: ";" }), "\n"] })] }) }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Why we write this React code:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "import TimerManager from './TimerManager'" }), " imports your custom timer management component"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "import './styles.css'" }), " imports the CSS file for professional styling"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "" }), " uses your component as a JSX element"] }), "\n", _jsx(_components.li, { children: "The App component acts as the root component that renders the timer management system" }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates React's component composition - how you build complex applications by combining focused, reusable components with their own state and cleanup logic."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " to see your complete React timer management application! The TimerManager component is now rendered inside the App component."] }), "\n", _jsx(_components.h3, { children: "Step 8: Test Complete Memory Management" }), "\n", _jsx(_components.p, { children: "Let's verify that your cleanup functions are working correctly by testing the complete integration between multiple timers, state management, and memory cleanup." }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Testing Steps:" }) }), "\n", _jsxs(_components.ol, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Create Multiple Timers" }), ": Click \"Add New Timer\" several times to create 3-4 timers"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Start Some Timers" }), ": Start 2-3 timers and watch them count independently"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Remove Running Timer" }), ": Remove a timer that's currently running and watch the console"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Check Cleanup Stats" }), ": Notice the cleanup count increases when timers are removed"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Remove All Timers" }), ": Use \"Remove All Timers\" and watch multiple cleanup events"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Memory Efficiency" }), ": See the memory efficiency percentage showing proper cleanup"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "What's Happening Behind the Scenes:" }) }), "\n", _jsxs(_components.ol, { children: ["\n", _jsx(_components.li, { children: "Each Timer component creates its own useEffect for interval management" }), "\n", _jsx(_components.li, { children: "When timers are started, setInterval creates recurring operations" }), "\n", _jsx(_components.li, { children: "When timers are stopped or removed, cleanup functions run automatically" }), "\n", _jsx(_components.li, { children: "clearInterval cancels the timer intervals, preventing memory leaks" }), "\n", _jsx(_components.li, { children: "Cleanup events are reported to the parent for monitoring" }), "\n", _jsx(_components.li, { children: "Memory management statistics show the effectiveness of cleanup functions" }), "\n"] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "React Concept Applied" }), ": This demonstrates the complete React cleanup lifecycle - how multiple components with their own effects and cleanup functions coordinate to prevent memory leaks and ensure efficient resource usage."] }), "\n", _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Click \"Run\"" }), " and thoroughly test your timer management system! Try creating many timers, starting them, and then removing them. Watch the cleanup statistics show perfect memory management!"] }), "\n", _jsx(_components.h2, { children: "Congratulations!" }), "\n", _jsx(_components.p, { children: "You've successfully built your first React application with comprehensive cleanup and memory management! You've applied crucial React resource management concepts:" }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "React Concepts Mastered:" }) }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Effect Cleanup Functions" }), ": Used cleanup functions to cancel timers and prevent memory leaks"] }), "\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Memory Management" }), ": Implemented professional patterns for resource tracking and cleanup"] }), "\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Multiple Component Coordination" }), ": Managed multiple Timer components with independent cleanup requirements"] }), "\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Resource Lifecycle Management" }), ": Coordinated timer creation, operation, and cleanup across component lifecycle"] }), "\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Event-Driven Architecture" }), ": Used custom events to track cleanup operations across components"] }), "\n", _jsxs(_components.li, { children: ["✅ ", _jsx(_components.strong, { children: "Professional Monitoring" }), ": Implemented memory management monitoring to visualize cleanup effectiveness"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Real-World Applications:" }) }), "\n", _jsx(_components.p, { children: "This timer management system demonstrates patterns you'll use in every professional React application:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Real-time Dashboards" }), ": Multiple data refresh timers with proper cleanup when views change"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Gaming Applications" }), ": Animation loops and game timers that clean up when games end"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Chat Applications" }), ": Typing indicators and presence timers with automatic cleanup"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Productivity Apps" }), ": Work session timers, break reminders, and task tracking with memory management"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Media Applications" }), ": Playback timers, progress tracking, and subtitle synchronization"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "What You've Built:" }) }), "\n", _jsx(_components.p, { children: "Your timer management application showcases React's cleanup strengths:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Multiple Independent Timers" }), ": Each timer operates independently with its own state and cleanup"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Automatic Memory Management" }), ": Cleanup functions prevent memory leaks when timers are removed"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Professional Monitoring" }), ": Real-time statistics show cleanup effectiveness and memory efficiency"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Scalable Architecture" }), ": Pattern works for any number of timers without performance degradation"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Professional Development Patterns:" }) }), "\n", _jsx(_components.p, { children: "You've learned industry-standard React practices:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Component Separation" }), ": Each component in its own file with focused responsibilities"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Cleanup Functions" }), ": Systematic approach to preventing memory leaks and resource waste"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Resource Tracking" }), ": Professional patterns for monitoring and managing application resources"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Event-Driven Communication" }), ": Modern patterns for component coordination and monitoring"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "The Power of Cleanup Functions:" }) }), "\n", _jsx(_components.p, { children: "You've experienced how cleanup functions transform React applications:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Memory Leak Prevention" }), ": No orphaned timers consuming resources after removal"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Professional Quality" }), ": Reliable, efficient resource management matching industry standards"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Scalable Performance" }), ": Application maintains optimal performance regardless of timer usage"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Predictable Behavior" }), ": Clean, reliable component lifecycle management"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Memory Management Impact Visualization:" }) }), "\n", _jsx(_components.p, { children: "Your cleanup statistics demonstrate the real impact of proper memory management:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Perfect Cleanup" }), ": 100% memory efficiency when timers are properly removed"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Resource Tracking" }), ": Clear visibility into resource allocation and cleanup"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Professional Monitoring" }), ": Same patterns used in production applications for performance tracking"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Educational Value" }), ": Visual proof of cleanup function effectiveness"] }), "\n"] }), "\n", _jsx(_components.p, { children: "You're now ready to build sophisticated React applications with proper resource management, real-time features, and professional-quality memory handling. Every React concept you'll learn builds on these cleanup fundamentals you've just mastered!" }), "\n", _jsx(_components.p, { children: "The smooth timer management experience you've created might seem straightforward, but you've just implemented the same cleanup patterns used in the most sophisticated React applications worldwide. When you see those timers start and stop cleanly without memory leaks, you're experiencing the same React resource management magic that powers applications used by millions of people every day." }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Performance Impact Demonstration:" }) }), "\n", _jsx(_components.p, { children: "Your timer management system shows the real benefits of cleanup functions:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Without Cleanup" }), ": Removing timers would leave intervals running, consuming CPU and memory"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "With Cleanup" }), ": Timers are completely cleaned up when removed, freeing all resources"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Memory Efficiency" }), ": 100% cleanup rate ensures optimal resource usage"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Professional Quality" }), ": Same resource management patterns used by major applications"] }), "\n"] }), "\n", _jsx(_components.p, { children: _jsx(_components.strong, { children: "Professional Development Skills:" }) }), "\n", _jsx(_components.p, { children: "You've learned essential skills for React career advancement:" }), "\n", _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Memory Management" }), ": Critical skill for senior React developer positions"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Resource Optimization" }), ": Understanding of performance techniques valued by employers"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Production Readiness" }), ": Applications you build can handle real-world usage patterns"] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Problem Solving" }), ": Ability to prevent and debug memory-related issues"] }), "\n"] }), "\n", _jsx(_components.p, { children: "Welcome to professional-grade React resource management. You now have the skills to build reliable, scalable React applications that provide excellent user experiences while maintaining optimal performance and memory usage!" }), "\n", _jsx(_components.p, { children: "The cleanup patterns you've mastered are the foundation for every advanced React concept you'll learn - from custom hooks and API integration to real-time applications and performance optimization. Master these fundamentals, and you'll be ready to build any React application you can imagine!" })] }); } function MDXContent(props = {}) { const {wrapper: MDXLayout} = { ..._provideComponents(), ...props.components }; return MDXLayout ? _jsx(MDXLayout, { ...props, children: _jsx(_createMdxContent, { ...props }) }) : _createMdxContent(props); } return { default: MDXContent };