Kangax compatibility tables

Kangax compatibility tables
Name	Kangax compatibility tables
Author	Juriy "kangax" Zaytsev
Released	2010s
Genre	Compatibility matrix
License	Public domain (varies)

Kangax compatibility tables

Kangax compatibility tables are widely cited online matrices evaluating ECMAScript, JavaScript, WebGL, and related feature support across browsers and JavaScript engines. They serve as practical reference points for developers using Mozilla Firefox, Google Chrome, Apple Safari, Microsoft Edge, Opera, Node.js, V8, SpiderMonkey, and JavaScriptCore by summarizing which features of standards and proposals are implemented. Maintained by Juriy Zaytsev and contributors, the tables bridge specification texts from ECMA International and WHATWG to real-world implementations used by projects such as React, Angular, and Vue.js.

Overview

The tables aggregate information about features from standards and proposals including ECMAScript 6, ECMAScript 2016, ECMAScript 2017, ECMAScript 2018, ongoing TC39 proposals, and APIs from groups like W3C and WHATWG. They present per-feature support statuses for engines and browsers such as V8, ChakraCore, Hermes, SpiderMonkey, and server runtimes like Node.js and Deno. Commonly consulted by contributors to projects like Babel, TypeScript, Webpack, and Babel polyfill efforts, the tables inform transpilation, polyfill, and feature-detection strategies used by teams at companies such as Google, Microsoft, Apple, Facebook, and Mozilla.

History and Development

The work began as a community-driven effort by Juriy Zaytsev in the early 2010s to track ECMAScript 6 features against browser implementations emerging from competition among Google Chrome, Mozilla Firefox, and Apple Safari. Over time contributors from organizations including Microsoft, Amazon, and independent developers added test results for proposals from the TC39 committee, and for APIs standardized by W3C and WHATWG. The project evolved alongside parallel efforts such as Can I Use and the What Web Can Do Today initiative, and influenced compatibility tracking in ecosystems like npm and standards compliance reporting used by browser vendors at events like Mozilla Developer Conference and Google I/O.

Structure and Coverage

The tables are organized by standard, proposal stage, and web API category; entries include language features, syntax forms, built-in objects, and runtime behaviors. Coverage spans ECMAScript editions, DOM and HTML APIs from WHATWG, graphics and shader capabilities tied to WebGL, and newer proposals at various TC39 stages. Rows list features, while columns list targets such as Google Chrome, Mozilla Firefox, Apple Safari, Microsoft Edge Legacy, Edge (Chromium), Opera, and embedded/runtime environments like Node.js, enabling cross-comparison for developers building applications with frameworks like Next.js and Gatsby.

Methodology and Testing Criteria

Test methodology combines manual verification, automated test harnesses, and community-submitted results. Tests reference normative language from ECMA International specifications and test262 suites, interoperability reports, and dedicated feature tests similar to those used in projects like Test262 and W3C Test Suite. Criteria for a positive support entry typically require passing of specific conformance cases and observed behavior matching specification text as implemented in engines such as V8 and SpiderMonkey. Community governance and issue tracking leverage platforms like GitHub and discussion in venues attended by implementers from Google, Mozilla, and Microsoft.

Impact and Adoption

The tables have influenced tooling, polyfill libraries, and transpilers: projects like Babel and core-js use such compatibility knowledge to decide which transforms or shims to include. They have been cited in technical documentation from browser vendors including Mozilla Developer Network, in blog posts by engineers at Google and Microsoft, and in academic and industry analyses of web feature adoption. Enterprises and open-source projects including Facebook, Netflix, and LinkedIn consult compatibility matrices to set minimum supported browser lists and to prioritize progressive enhancement strategies.

Criticism and Limitations

Critics note that snapshot-style matrices can lag behind rapid implementation updates in engines like V8 and projects like Node.js, and that binary support indicators may oversimplify partial or behind-flags implementations found in Chrome Canary or nightly builds of Firefox Nightly. The reliance on community reporting and the absence of comprehensive formal proofs mean discrepancies can arise compared to results from rigorous conformance suites run by organizations such as W3C or ECMA International. Additionally, the focus on browser engines may underrepresent platform-specific behaviors in environments like Electron or embedded systems used by companies such as Samsung and Sony.

Category:Web development