Browser Compatibility Features Checked by UCE

Review 105 static browser compatibility rules for JavaScript, CSS, HTML, and Web APIs across desktop and mobile browser targets.

UCE compares detected feature usage with configured browser targets and suggests fallbacks where available. These are static compatibility checks, not runtime browser tests.

This index contains 105 unique named catalog entries generated directly from the same versioned UCE knowledge used by the analyzer.

web-api (52)

WebGPU

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: webgpu; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Feature-detect navigator.gpu and provide a fallback.
View Transitions API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: view-transitions; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Feature-detect startViewTransition and provide a normal transition fallback.
Popover API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: popover; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Feature-detect the Popover API or provide a dialog/menu fallback.
structuredClone()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: structured-clone; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Use a compatible clone fallback for older browsers.
ResizeObserver

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: resize-observer; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Load a ResizeObserver polyfill when older browsers are supported.
IntersectionObserver

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: intersection-observer; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Load a polyfill or provide an eager-loading fallback for older browsers.
AbortController

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: abort-controller; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Use a cancellation fallback or polyfill for older targets.
Async Clipboard API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: clipboard; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Feature-detect clipboard access and provide a manual copy fallback.
BroadcastChannel

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: broadcast-channel; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Use a storage-event or server-mediated fallback for older browsers.
HTML dialog element

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: dialog; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide dialog semantics and focus management through a compatible fallback.
Web Bluetooth

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: web-bluetooth; Minimum-version data for Chrome, Edge.

Recommendation: Treat Web Bluetooth as an enhancement and provide a non-Bluetooth path.
File System Access API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: file-system-access; Minimum-version data for Chrome, Edge.

Recommendation: Provide input/download fallbacks when native file-system access is unavailable.
Fetch API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: fetch; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Fetch API when supporting older browser targets.
WebSocket

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: websocket; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile WebSocket when supporting older browser targets.
Service Worker

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: service-worker; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Service Worker when supporting older browser targets.
Web Worker

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: web-worker; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Web Worker when supporting older browser targets.
IndexedDB

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: indexeddb; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile IndexedDB when supporting older browser targets.
Notifications API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: notifications; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Notifications API when supporting older browser targets.
Geolocation API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: geolocation; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Geolocation API when supporting older browser targets.
MediaDevices

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: media-devices; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile MediaDevices when supporting older browser targets.
Web Share API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: web-share; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Web Share API when supporting older browser targets.
Payment Request API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: payment-request; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Payment Request API when supporting older browser targets.
Credential Management API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: credentials; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Credential Management API when supporting older browser targets.
Permissions API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: permissions; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Permissions API when supporting older browser targets.
PerformanceObserver

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: performance-observer; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile PerformanceObserver when supporting older browser targets.
MutationObserver

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: mutation-observer; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile MutationObserver when supporting older browser targets.
requestIdleCallback

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: request-idle-callback; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile requestIdleCallback when supporting older browser targets.
OffscreenCanvas

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: offscreen-canvas; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile OffscreenCanvas when supporting older browser targets.
WebGL 2

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: webgl2; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile WebGL 2 when supporting older browser targets.
WebRTC

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: webrtc; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile WebRTC when supporting older browser targets.
Screen Orientation API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: screen-orientation; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Screen Orientation API when supporting older browser targets.
Fullscreen API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: fullscreen; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Fullscreen API when supporting older browser targets.
Picture-in-Picture API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: picture-in-picture; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Picture-in-Picture API when supporting older browser targets.
Screen Wake Lock API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: wake-lock; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Screen Wake Lock API when supporting older browser targets.
Speech Recognition

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: speech-recognition; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Speech Recognition when supporting older browser targets.
Speech Synthesis

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: speech-synthesis; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Speech Synthesis when supporting older browser targets.
URLPattern

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: url-pattern; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile URLPattern when supporting older browser targets.
CompressionStream

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: compression-stream; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CompressionStream when supporting older browser targets.
TransformStream

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: transform-stream; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile TransformStream when supporting older browser targets.
TextEncoder

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: text-encoder; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile TextEncoder when supporting older browser targets.
Web Crypto

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: crypto-subtle; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Web Crypto when supporting older browser targets.
Custom Elements

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: custom-elements; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Custom Elements when supporting older browser targets.
Shadow DOM

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: shadow-dom; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Shadow DOM when supporting older browser targets.
Web Animations API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: element-animate; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Web Animations API when supporting older browser targets.
ScrollIntoView options

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: scroll-into-view; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile ScrollIntoView options when supporting older browser targets.
matchMedia

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: match-media; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile matchMedia when supporting older browser targets.
Visual Viewport API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: visual-viewport; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Visual Viewport API when supporting older browser targets.
Network Information API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: network-information; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Network Information API when supporting older browser targets.
Device Memory API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: device-memory; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Device Memory API when supporting older browser targets.
Hardware concurrency

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: hardware-concurrency; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Hardware concurrency when supporting older browser targets.
Vibration API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: vibration; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Vibration API when supporting older browser targets.
Gamepad API

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: gamepad; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Gamepad API when supporting older browser targets.

css (31)

CSS :has()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-has; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide a fallback selector for browsers below the :has() baseline.
CSS container queries

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: container-queries; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide a media-query or layout fallback when container queries are unavailable.
CSS nesting

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-nesting; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Compile nested CSS or provide unnested rules for older targets.
CSS subgrid

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-subgrid; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide a regular grid fallback for browsers without subgrid.
CSS color-mix()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: color-mix; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide a precomputed color fallback before color-mix().
CSS backdrop-filter

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: backdrop-filter; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Provide a background fallback for browsers without backdrop-filter.
CSS :focus-visible

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: focus-visible; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Keep a safe :focus fallback for keyboard focus styling.
CSS Grid

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-grid; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS Grid when supporting older browser targets.
Flexbox gap

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-flex-gap; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Flexbox gap when supporting older browser targets.
CSS logical properties

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-logical; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS logical properties when supporting older browser targets.
CSS clamp()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-clamp; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS clamp() when supporting older browser targets.
CSS minmax()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-minmax; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS minmax() when supporting older browser targets.
CSS aspect-ratio

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-aspect-ratio; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS aspect-ratio when supporting older browser targets.
CSS sticky positioning

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-sticky; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS sticky positioning when supporting older browser targets.
CSS scroll snap

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-scroll-snap; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS scroll snap when supporting older browser targets.
CSS custom properties

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-variables; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS custom properties when supporting older browser targets.
CSS masks

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-masks; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS masks when supporting older browser targets.
CSS overscroll-behavior

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-overscroll; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS overscroll-behavior when supporting older browser targets.
CSS accent-color

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-accent-color; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS accent-color when supporting older browser targets.
CSS cascade layers

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-cascade-layers; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS cascade layers when supporting older browser targets.
CSS :is()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-is; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS :is() when supporting older browser targets.
CSS :where()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-where; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS :where() when supporting older browser targets.
CSS :any-link

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-any-link; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS :any-link when supporting older browser targets.
CSS ::marker

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-marker; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS ::marker when supporting older browser targets.
CSS ::placeholder

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-placeholder; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS ::placeholder when supporting older browser targets.
CSS motion path

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-motion-path; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS motion path when supporting older browser targets.
CSS text-wrap balance

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-text-wrap-balance; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS text-wrap balance when supporting older browser targets.
Dynamic viewport units

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-dvh; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Dynamic viewport units when supporting older browser targets.
CSS LCH colors

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-lch; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS LCH colors when supporting older browser targets.
CSS relative colors

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-relative-color; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS relative colors when supporting older browser targets.
CSS @scope

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: css-scope; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile CSS @scope when supporting older browser targets.

javascript (22)

Import maps

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: import-maps; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Bundle imports or provide an import-map fallback for older browsers.
Optional chaining

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: optional-chaining; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Transpile optional chaining for older browser targets.
Nullish coalescing

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: nullish-coalescing; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Transpile nullish coalescing for older browser targets.
Promise.allSettled()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: promise-all-settled; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Polyfill Promise.allSettled or use an equivalent aggregation strategy.
BigInt

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: bigint; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Avoid BigInt on older targets or provide a compatible numeric library.
Array.prototype.at()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: array-at; Minimum-version data for Chrome, Edge, Firefox, Safari.

Recommendation: Transpile or replace .at() when supporting older browsers.
Async functions

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: async-await; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Async functions when supporting older browser targets.
JavaScript modules

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: modules; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile JavaScript modules when supporting older browser targets.
Dynamic import

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: dynamic-import; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Dynamic import when supporting older browser targets.
Private class fields

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: private-fields; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Private class fields when supporting older browser targets.
Logical assignment operators

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: logical-assignment; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Logical assignment operators when supporting older browser targets.
Numeric separators

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: numeric-separator; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Numeric separators when supporting older browser targets.
Object.fromEntries()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: object-from-entries; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Object.fromEntries() when supporting older browser targets.
globalThis

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: global-this; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile globalThis when supporting older browser targets.
Promise.any()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: promise-any; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Promise.any() when supporting older browser targets.
WeakRef

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: weak-ref; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile WeakRef when supporting older browser targets.
Array.prototype.flat()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: array-flat; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Array.prototype.flat() when supporting older browser targets.
String.replaceAll()

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: string-replace-all; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile String.replaceAll() when supporting older browser targets.
Intl.Segmenter

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: intl-segmenter; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Intl.Segmenter when supporting older browser targets.
Intl.ListFormat

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: intl-list-format; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Intl.ListFormat when supporting older browser targets.
Top-level await

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: top-level-await; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile Top-level await when supporting older browser targets.
RegExp lookbehind

Checks this feature against configured desktop and mobile browser targets.

Support: Static analysis only. Evidence: Rule ID: regexp-lookbehind; Minimum-version data for Chrome, Edge, Firefox, Safari, Chrome Android, Safari iOS.

Recommendation: Feature-detect or compile RegExp lookbehind when supporting older browser targets.

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