browser.webkit only api

browser.webkit-only-api

Rule ID: browser.webkit-only-api Severity: WARN Category: browser Target Standards: W3C Fullscreen API Specification, W3C Web Audio API Specification, W3C Web Speech API Specification

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1. Overview & Core Invariant

Flags direct invocation of WebKit-prefixed legacy APIs without standard W3C equivalents or graceful fallbacks

Core Invariant:

"Direct invocation of WebKit-prefixed methods ('webkitRequestFullscreen', 'webkitAudioContext', etc.) must provide standard W3C fallbacks for non-WebKit browsers."

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2. Technical Grounding & Engine Realities

WebKit vendor-prefixed APIs were transitional features during early HTML5 standardization.

Calling them directly without checking W3C standard methods causes instant runtime crashes in Mozilla Firefox desktop and modern Chromium environments.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Crash in Firefox and Non-WebKit Browsers	MEDIUM	Methods like 'element.webkitRequestFullscreen()' throw 'TypeError: not a function' in Firefox because Gecko does not implement WebKit prefixes.
Missed W3C Standard Improvements	LOW	Legacy WebKit methods lack updated return types (such as Promises) supported by modern standard W3C APIs.

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4. Non-Compliant Code Patterns (Bad Examples)

JAVASCRIPT (Direct invocation of WebKit fullscreen without standard check):

function enterFullscreen(element) {
  element.webkitRequestFullscreen();
}

JAVASCRIPT (Direct instantiation of webkitAudioContext):

const audioCtx = new webkitAudioContext();

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5. Compliant Implementation Patterns (Good Examples)

JAVASCRIPT (Prioritizing standard W3C method with WebKit fallback):

function enterFullscreen(element) {
  if (element.requestFullscreen) {
    element.requestFullscreen();
  } else if (element.webkitRequestFullscreen) {
    element.webkitRequestFullscreen();
  }
}

JAVASCRIPT (Standard AudioContext fallback chain):

const AudioContextClass = window.AudioContext || window.webkitAudioContext;
const audioCtx = new AudioContextClass();

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6. How to Suppress (Ignore Directives)

If this pattern is required for an intentional exception, suppress the diagnostic using the canonical Charites Rule ID:

<!-- charites:ignore browser.webkit-only-api intentional exception -->

// charites:ignore browser.webkit-only-api intentional exception

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7. Configuration Reference (charites.yaml)

rules:
  browser.webkit-only-api:
    severity: warn # error | warn | info | off

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8. Architectural Domain & Verification Reference

• Domain Architecture & Analysis Pipeline: See the browser Category Guide.
• 1-SSOT Golden Tri-Corpus Test Matrix: See the Verification Harness on the Master Home page.
• Rule Catalog Index: See Master Wiki Home.