Editing ECMAScript (section)

== Conformance ==
In 2010, Ecma International started developing a standards test for Ecma 262 ECMAScript.<ref>{{cite web |url=http://test262.ecmascript.org/ |title=ECMAScript Language – test262 |publisher=Test262.ecmascript.org |access-date=2013-10-31 |url-status=dead |archive-url=https://web.archive.org/web/20110514205704/http://test262.ecmascript.org/ |archive-date=2011-05-14 }}</ref>
Test262 is an ECMAScript conformance test suite that can be used to check how closely a JavaScript implementation follows the ECMAScript Specification. The test suite contains thousands of individual tests, each of which tests some specific requirement(s) of the ECMAScript specification. The development of Test262 is a project of the Ecma Technical Committee 39 (TC39). The testing framework and the individual tests are contributed to Ecma by member organizations of TC39.

Important contributions were made by Google ([[Sputnik (JavaScript conformance test)|Sputnik test suite]]) and Microsoft, who both contributed thousands of tests.
The Test262 test suite consisted of {{val|38014}} tests {{as of|2020|01|lc=y}}.<ref name="GitHub 2020">{{cite web | title=tc39/test262 | website=GitHub | date=January 24, 2020 | url=https://github.com/tc39/test262 | access-date=January 29, 2020 | archive-date=October 1, 2019 | archive-url=https://web.archive.org/web/20191001032806/https://github.com/tc39/test262 | url-status=live }}</ref> ECMAScript specifications through ES7 are well-supported in major [[web browser]]s. The table below shows the conformance rate for current versions of software with respect to the most recent editions of ECMAScript.

{| class="wikitable sortable"
|+Scripting engine conformance
|- style="background:#ccf;"
! scope="col" rowspan="2" | Scripting engine
! scope="col" rowspan="2" | Reference application(s)
! scope="col" colspan="4" | Conformance<ref>ES5 is the baseline for this test suite. The conformance rate for other editions reflects support for new features only, not a comprehensive score.</ref>
|-
!scope="col" | ES5<ref name="kangax5">{{cite web |date=2024-04-14 |title=ECMAScript 5 compatibility table |url=https://compat-table.github.io/compat-table/es5/ |url-status=live |archive-url=https://web.archive.org/web/20240114035054/https://compat-table.github.io/compat-table/es5/ |archive-date=2024-01-14 |access-date=2024-04-14 |website=compat-table.github.io |language=en}}</ref>
!scope="col" | ES6 (2015)<ref name="kangax6">{{cite web |date=2024-04-14 |title=ECMAScript 6 compatibility table |url=https://compat-table.github.io/compat-table/es6/ |url-status=live |archive-url=https://web.archive.org/web/20240404212624/https://compat-table.github.io/compat-table/es6/ |archive-date=2024-04-04 |access-date=2024-04-14 |website=compat-table.github.io |language=en}}</ref>
!scope="col" | ES2016+<ref name="kangax2016plus">{{cite web |date=2024-04-14 |title=ECMAScript 2016+ compatibility table |url=https://compat-table.github.io/compat-table/es2016plus/ |url-status=live |archive-url=https://web.archive.org/web/20240114034945/https://compat-table.github.io/compat-table/es2016plus/ |archive-date=2024-01-14 |access-date=2024-04-14 |website=compat-table.github.io |language=en}}</ref>
!scope="col" | Next<ref>{{Cite web |date=2024-04-14 |title=ECMAScript Next compatibility table |url=https://compat-table.github.io/compat-table/esnext/ |url-status=live |archive-url=https://web.archive.org/web/20240114035113/https://compat-table.github.io/compat-table/esnext/ |archive-date=2024-01-14 |access-date=2024-04-14 |website=compat-table.github.io}}</ref><ref>Composite score that includes new features from ES7 through next edition drafts</ref>
|-
!scope="row" | [[SpiderMonkey]]
| [[Firefox]] 120
| 100% || 98% || 98% || 5%
|-
!scope="row" | [[V8 (JavaScript engine)|V8]]
| [[Google Chrome]] 117, [[Microsoft Edge]] 113, [[Opera (web browser)|Opera]] 98
| 100% || 98% || 98% || 5%
|-
!scope="row" | [[JavaScriptCore]]
| [[Safari (web browser)|Safari]] 17
| 99% || 100% || 98% || 11%
|}