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What is test262.fyi?

trflynn89/test262.fyi — explained in plain English

Analysis updated 2026-07-18 · repo last pushed 2026-03-18

JavaScriptAudience · developerComplexity · 4/5MaintainedSetup · hard

In one sentence

test262.fyi is a public dashboard that tests JavaScript engines like V8 and SpiderMonkey against the official test262 spec and publishes daily pass/fail results.

Mindmap

mindmap
  root((repo))
    What it does
      Runs test262 suite
      Tests JS engines daily
      Publishes results online
    Tech stack
      JavaScript
      test262 suite
    Use cases
      Compare engine spec compliance
      Track new feature adoption
      Benchmark a new engine
    Audience
      Engine developers
      Language designers

Code map

Detail Auto

An interactive map of this repo's files and how they connect — its source is parsed live in your browser. Click Visualize to build it.

filefunction / class

What do people build with it?

USE CASE 1

Check how V8, SpiderMonkey, JavaScriptCore, and other engines comply with the official JavaScript spec.

USE CASE 2

Watch how different engines adopt a newly proposed JavaScript feature over time.

USE CASE 3

Compare a new experimental JavaScript engine's progress against established ones.

USE CASE 4

Get early visibility into upcoming JavaScript capabilities still being implemented by engines.

What is it built with?

JavaScript

How does it compare?

trflynn89/test262.fyi3rd-eden/ircb.ioa15n/a15n
LanguageJavaScriptJavaScriptJavaScript
Last pushed2026-03-182016-11-162019-04-07
MaintenanceMaintainedDormantDormant
Setup difficultyhardeasyeasy
Complexity4/52/52/5
Audiencedeveloperdevelopergeneral

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · hard Time to first run · 1day+

Built for specific high-powered hardware and not meant to be run by individuals, it's a public service you visit, not something you deploy yourself.

Copy-paste prompts

Prompt 1
Explain what test262 is and why test262.fyi runs it against multiple JavaScript engines daily.
Prompt 2
Help me understand how to compare V8's and SpiderMonkey's compliance results on test262.fyi for a specific JS feature.
Prompt 3
Walk me through how this project could track which test262 pull requests affect different engines.
Prompt 4
Explain how I'd interpret test262.fyi's results if I were building a new experimental JavaScript engine.

Frequently asked questions

What is test262.fyi?

test262.fyi is a public dashboard that tests JavaScript engines like V8 and SpiderMonkey against the official test262 spec and publishes daily pass/fail results.

What language is test262.fyi written in?

Mainly JavaScript. The stack also includes JavaScript.

Is test262.fyi actively maintained?

Maintained — commit in last 6 months (last push 2026-03-18).

How hard is test262.fyi to set up?

Setup difficulty is rated hard, with roughly 1day+ to a first successful run.

Who is test262.fyi for?

Mainly developer.

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