- Semantic Elements (main, nav, footer, etc)
- Custom Elements / Extended Elements (polyfill for safari)
- Email, URL, Range, Date, Search inputs
- Form validation
- Datalist - built-in autocomplete
- Input Minimum / Pattern / Suggestions
- Button type (not all form buttons submit)
- Dialog
- ­ page-break hyphen hint
- Picture Element
- SVG & WebP (supports anim and alpha)
- MP3 or Opus audio codecs
- Template & Slot Element
- Summary & Details Elements
- (Date) Time Element
- Script module type
- Feature Support Queries
- Media Queries - Size Breakpoints (no vars), Print (pages), DPI, dark mode, reduced motion, contrast
- Import (great combined with queries)
- Nesting (newest browsers)
- Grid, Flexbox, Columns
- :is() & :where() selectors
- Animation & transition
- Transform
- Viewport Units: vh, vw
- hsla color values
- calc & var (great for colors, font sizes)
- math min(), max() and clamp()
- border images (9-slice borders)
- object- fit/position
- hanging-punctuation (safari or fallback)
- WOFF & WOFF2 web font format
- system-ui font family (with fallbacks)
- CSS Snap Points (tutorial)
- Resizable
- aspect-ratio
- Input in-/out-of-range
- const and let (var alternatives)
- Array includes, some and every
- String includes, padStart/padEnd
- Nullish Coalescence (“??”)
- Optional Chaining (“?.”)
- Event Listener once option
- Modules (include) & Classes
- Exponentiation operator
- Object literal property shorthand
- Arrow Functions (lambda equivalent)
- Template literals (better string building)
- Args: Default, Rest & Spread
- Intl.ListFormat (polyfill required)
- Web Animations API (partial)
- Drag and Drop
- Promises async, await, for… on
- Generators yield, for…of
- Map, Set, WeakMap, WeakSet
- Fetch & URLSearchParams
- Websockets
- Web Workers
- Service Worker (push & cache)
- Web Storage ([session|local]Storage)
- IndexedDB (2.0) (bigger storage)
- WebRTC
- Speech Synthesis & Recognition
- Canvas [2d, webGL]
- Web Cryptography
- Web Payments
- JSDoc - Documentation and Typing
- Standard Style - the new style rules
- Web App Manifest (PWA)
- Add to Homescreen Prompt
- Service Worker (caching and more)
- WebAssembly (higher-performance, compiled code)
- All Browsers on iOS are Safari - as of 2023…