tc39/test262 resource

Health v2 · maintenance only

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Adoption not part of the score

2813 stars · 558 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Test262 is the official conformance test suite for the ECMAScript (JavaScript) language specifications, including ECMA-262, ECMA-402, and ECMA-404. It contains over 50,000 test files used to verify that JavaScript engines, parsers, and runtimes correctly implement the specification.

Use cases

• verify a JavaScript engine conforms to the ECMAScript spec
• test a new JS runtime implementation against the official test suite
• check parser compliance with ECMAScript grammar
• validate internationalization API behavior in a JS engine
• write conformance tests for a new Stage 4 language proposal
• compare spec compliance across JavaScript engines

When to choose

• you are building or maintaining a JavaScript engine, parser, or runtime
• you need to verify spec compliance for a Stage 4 proposal implementation
• you want the authoritative, comprehensive ECMAScript test corpus

When to avoid

• you need unit tests for your own application code
• you want a general-purpose JavaScript testing framework like Jest or Mocha
• you need browser end-to-end testing

Facets

dataset · maturity active

testing e2e-testing parser interpreter programming-languages testing developer-tools cli cross-platform ecmascript conformance-suite javascript-engine tc39 spec-compliance test-runner localization nodejs

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