Javascript Polyfills Roadmap
18 sections • 278 topics
- 1. Feature Detection Techniques (typeof, in, hasOwnProperty)
- Example: Comprehensive feature detection pattern
- 2. typeof and in Operator for Checking Features
- Example: typeof vs in operator comparison
- 3. try-catch Blocks for Safe Feature Testing
- Example: Safe storage detection with try-catch
- 4. CSS.supports() API for Style Detection
- Example: CSS feature detection patterns
- 5. Modernizr Library Integration and Custom Builds
- Example: Modernizr usage patterns
- 6. Dynamic Import for Conditional Polyfill Loading
- Example: Dynamic polyfill loading strategies
- Key Takeaways - Feature Detection
- 1. Polyfill Structure and Template Patterns
- Example: Complete polyfill template structure
- 2. Prototype Extension (Array.prototype, String.prototype)
- Example: Proper prototype extension with defineProperty
- 3. Static Method Polyfills (Object.assign, Array.from)
- Example: Static method polyfills
- 4. Object.defineProperty for Non-enumerable Methods
- Example: Advanced defineProperty usage patterns
- 5. UMD and ES Module Polyfill Patterns
- Example: UMD wrapper pattern
- 6. Idempotency and Safe Polyfill Execution
- Example: Idempotent polyfill patterns
- Key Takeaways - Polyfill Writing
- 1. Array Methods (map, filter, reduce, find, includes)
- Example: Array.prototype.map polyfill
- Example: Array.prototype.find and findIndex polyfills
- Example: Array.prototype.includes polyfill (handles NaN)
- 2. Object Methods (Object.assign, keys, values, entries)
- Example: Object.assign polyfill
- Example: Object.keys, values, and entries polyfills
- 3. String Methods (includes, startsWith, endsWith, padStart)
- Example: String search method polyfills
- Example: String padding polyfills
- 4. Number Methods (Number.isNaN, isFinite, isInteger)
- Example: Number static method polyfills
- 5. Symbol and Symbol Registry Implementation
- Example: Basic Symbol polyfill (limited functionality)
- 6. Iterator Protocol and Generator Polyfills
- Example: Custom iterator implementation
- Key Takeaways - ECMAScript Features
- 1. Promise API (Promise.all, Promise.race, Promise.allSettled)
- Example: Simplified Promise polyfill core
- Example: Promise static method polyfills
- 2. Set and Map Collection Implementation
- Example: Set polyfill implementation
- Example: Map polyfill implementation
- 3. WeakSet and WeakMap Memory-aware Collections
- Example: WeakMap polyfill (limited - no weak references)
- 4. Proxy and Reflect API for Object Interception
- Example: Reflect API polyfill (without Proxy)
- 5. ES6 Class Syntax and super Keyword
- Example: Class syntax transpiled to ES5
- 6. Async/Await and Generator Function Support
- Example: Async/await transpilation pattern
- Example: Generator function transpilation
- Key Takeaways - ES6+ Features
- 1. querySelector and querySelectorAll Implementation
- Example: querySelector polyfill for very old browsers
- Example: getElementsByClassName polyfill for IE8
- 2. Element.classList API (add, remove, toggle)
- Example: classList polyfill for IE9
- 3. addEventListener and removeEventListener Polyfills
- Example: addEventListener polyfill for IE8
- 4. CustomEvent and Event Constructor API
- Example: CustomEvent polyfill
- Example: MouseEvent and KeyboardEvent polyfills
- 5. Element.matches and Selector API
- Example: Element.matches polyfill with vendor prefixes
- Example: Element.closest polyfill
- 6. Node.contains and DOM Traversal Methods
- Example: Node.contains polyfill
- Example: Element traversal property polyfills
- Key Takeaways - DOM APIs
- 1. Fetch API and AbortController Implementation
- Example: Simplified fetch polyfill using XMLHttpRequest
- Example: AbortController polyfill (simplified)
- 2. URL and URLSearchParams Constructor
- Example: URLSearchParams polyfill
- Example: Basic URL polyfill
- 3. FormData and File API for Form Handling
- Example: FormData polyfill extensions
- Example: File constructor polyfill
- 4. Blob and FileReader API for Binary Data
- Example: Blob.prototype methods polyfill
- Example: FileReader wrapper with Promise
- 5. requestAnimationFrame and Performance.now()
- Example: requestAnimationFrame polyfill with vendor prefixes
- Example: performance.now() polyfill
- 6. IntersectionObserver and ResizeObserver APIs
- Example: IntersectionObserver basic polyfill concept
- Example: ResizeObserver polyfill concept
- Key Takeaways - Web APIs
- 1. localStorage and sessionStorage Implementation
- Example: localStorage polyfill using cookies
- Example: Safe storage access with try-catch
- 2. IndexedDB API Compatibility and Polyfills
- Example: IndexedDB vendor prefix normalization
- 3. Cookie API and document.cookie Extensions
- Example: Cookie utility library
- Example: Storage wrapper using cookies as fallback
- 4. WebSQL to IndexedDB Migration Patterns
- Example: WebSQL migration helper
- 5. Memory-based Storage Fallback for Private Mode
- Example: Complete storage fallback implementation
- Example: Storage with JSON serialization helper
- Key Takeaways - Storage & Data Management
- 1. CSS Custom Properties (CSS Variables --var-name)
- Example: CSS Custom Properties polyfill
- 2. CSS Grid and Flexbox Layout Support
- Example: Flexbox vendor prefix polyfill
- Example: Grid gap polyfill with margins
- 3. CSS calc() Function Implementation
- Example: CSS calc() polyfill
- 4. Media Queries and matchMedia API
- Example: matchMedia polyfill
- Example: Prefers-color-scheme detection
- 5. Modern CSS Selectors (:has, :is, :where, :not)
- Example: :has() selector polyfill
- Example: :focus-visible polyfill
- 6. CSS Container Queries (@container) Polyfill
- Example: Container queries polyfill
- Example: Container query units polyfill (cqw, cqh)
- Key Takeaways - CSS & Styling
- 1. Custom Elements v1 API (customElements.define)
- Example: Custom Elements polyfill
- 2. Shadow DOM v1 API (attachShadow) and Limitations
- Example: Shadow DOM polyfill (simplified)
- 3. HTML Template Element (<template>) Polyfills
- Example: HTML Template polyfill
- 4. Slot Element and Content Projection Patterns
- Example: Slot element polyfill
- 5. HTML Imports and ES Module Alternatives
- Example: HTML Imports alternative with fetch
- Example: ES Module approach for Web Components
- 6. Scoped CSS and ::shadow Pseudo-element
- Example: Scoped CSS polyfill with data attributes
- Example: CSS-in-JS approach for components
- Key Takeaways - Web Components
- 1. requestIdleCallback for Background Tasks
- Example: requestIdleCallback polyfill
- Example: Enhanced polyfill with frame budget tracking
- 2. Web Animations API (element.animate) Polyfills
- Example: Basic Web Animations API polyfill
- 3. PerformanceObserver and Performance Timeline API
- Example: PerformanceObserver polyfill
- 4. IntersectionObserver and ResizeObserver Performance
- Example: Performance-optimized IntersectionObserver usage
- Example: Optimized ResizeObserver with debouncing
- 5. requestAnimationFrame and cancelAnimationFrame
- Example: Read/Write batching to avoid layout thrashing
- Example: Frame budget management
- Example: GPU-accelerated animations
- Key Takeaways - Performance & Animation
- 1. Prototype Pollution Prevention Techniques
- Example: Prototype pollution prevention
- Example: Creating pollution-proof objects
- 2. Content Security Policy (CSP) Compatible Polyfills
- Example: CSP-compatible polyfill patterns
- Example: CSP-safe CSS injection
- 3. Safe eval() Alternatives (Function constructor)
- Example: Safe alternatives to eval()
- Example: Safe setTimeout/setInterval usage
- 4. Third-party Polyfill Security Auditing
- Example: Polyfill security checklist
- 5. Supply Chain Security and Dependency Management
- Example: Subresource Integrity (SRI) for CDN polyfills
- Example: Package verification and lock file usage
- Key Takeaways - Security & CSP
- 1. Differential Serving (Modern vs Legacy Bundles)
- Example: Module/nomodule pattern
- Example: Dynamic differential serving
- 2. Dynamic import() and Code Splitting
- Example: Conditional polyfill loading
- Example: Progressive polyfill loader
- 3. Polyfill.io Service Integration and Configuration
- Example: Self-hosted polyfill service alternative
- 4. CDN-based Polyfill Loading (unpkg, jsdelivr)
- Example: CDN loading with fallback
- Example: Optimized CDN selection
- 5. Service Worker Caching for Offline Polyfills
- Example: Service Worker for polyfill caching
- Example: Stale-while-revalidate strategy
- 6. HTTP/2 Push and <link rel="preload">
- Example: Resource hints for polyfills
- Example: Dynamic preload injection
- Key Takeaways - Modern Loading & Distribution
- 1. Unit Testing with Jest, Mocha, or Jasmine
- Example: Jest unit tests for polyfills
- Example: Testing Promise polyfill
- 2. Cross-browser Testing (BrowserStack, Sauce Labs)
- Example: Playwright cross-browser tests
- Example: BrowserStack configuration
- 3. Feature Parity Testing and Validation
- Example: Feature parity test suite
- Example: Property-based testing
- 4. Performance Impact Measurement and Profiling
- Example: Performance benchmarking
- Example: Memory usage tracking
- 5. Automated Testing (Selenium, Playwright, Puppeteer)
- Example: Karma configuration for multi-browser testing
- Example: GitHub Actions CI workflow
- 6. Mock and Stub Patterns for Feature Detection
- Example: Mocking browser APIs
- Example: Sinon stubs for complex scenarios
- Key Takeaways - Testing & Quality Assurance
- 1. Lazy Loading and Conditional Polyfill Loading
- Example: Lazy polyfill loader with caching
- Example: Route-based polyfill loading
- 2. Feature Flags for Gradual Polyfill Rollout
- Example: Feature flag-based polyfill loading
- 3. Polyfill Composition and Dependency Trees
- Example: Dependency-aware polyfill loader
- Example: Composite polyfill bundles
- 4. Tree Shaking and Dead Code Elimination
- Example: Tree-shakeable polyfill structure
- Example: Conditional compilation for polyfills
- 5. Semantic Versioning for Polyfill Updates
- Example: Versioned polyfill management
- Example: Automated polyfill update workflow
- 6. Micro-polyfill Architecture (Single Feature Polyfills)
- Example: Micro-polyfill architecture
- Example: Ponyfill pattern (non-invasive)
- Key Takeaways - Advanced Patterns
- 1. Webpack with @babel/preset-env and core-js
- Example: Webpack 5 polyfill configuration
- Example: Conditional polyfill loading with Webpack
- 2. Babel Plugins and Transform Configuration
- Example: Babel configuration for polyfills
- Example: Custom Babel plugin for polyfills
- 3. Rollup and @rollup/plugin-babel Setup
- Example: Rollup configuration for polyfills
- 4. PostCSS Plugins for CSS Feature Polyfills
- Example: PostCSS configuration for CSS polyfills
- 5. ESLint Rules for Polyfill Code Quality
- Example: ESLint configuration for polyfills
- 6. TypeScript Definition Files (.d.ts) for Polyfills
- Example: TypeScript declarations for polyfills
- Example: Publishing TypeScript polyfill library
- Key Takeaways - Build Tools & Workflow
- 1. Internet Explorer 11 Required Polyfills
- Example: Complete IE11 polyfill bundle
- Example: IE11-specific Babel configuration
- 2. Safari and WebKit Specific Feature Gaps
- Example: Safari-specific polyfills
- 3. Android WebView and Mobile Browser Compatibility
- Example: Mobile browser detection and polyfills
- 4. Progressive Enhancement Strategy with Polyfills
- Example: Progressive enhancement pattern
- 5. Graceful Degradation for Unsupported Features
- Example: Graceful degradation utilities
- Key Takeaways - Legacy Browser Support
- 1. Polyfill Bundle Size Reduction Techniques
- Example: Bundle size optimization strategy
- 2. Runtime Performance Impact and Benchmarking
- Example: Performance monitoring system
- 3. Memory Usage and Garbage Collection Monitoring
- Example: Memory monitoring and optimization
- 4. Error Tracking (Sentry, Rollbar) for Polyfill Issues
- Example: Error tracking and monitoring integration
- 5. Deployment and Rollback Strategies
- Example: Deployment automation with canary strategy
- 6. A/B Testing for Polyfill Performance Impact
- Example: A/B testing framework for polyfills
- Key Takeaways - Enterprise & Production
- 1. Chrome DevTools and Firefox Developer Tools
- Example: DevTools debugging utilities
- 2. Common Polyfill Errors and Solutions
- Example: Common issue detection and fixes
- 3. Performance Profiling and Flame Charts
- Example: Performance profiling suite
- 4. Feature Detection Debugging in Console
- Example: Advanced feature detection utilities
- 5. Polyfill Conflict Resolution and Load Order
- Example: Conflict detection and resolution
- Key Takeaways - Debugging & Troubleshooting