Not yet stable

For a given set of browsers, what APIs are not yet in all of them.

Example Comparisons
Browsers
Features

Summary

A count of the number of APIs are in Browser X but not in Browser Y.
Not in EdgeNot in Firefox
In Edge 25
In Firefox 25

Unstable APIs

Below is a list of features that are not in all of Edge and Firefox

Raw Data

Quick Links:

JS Data

API First Browser Date Days in Limbo Notes
javascript.builtins.Atomics.Atomic_operations_on_non_shared_buffers Firefox7/28/20202196
javascript.builtins.Atomics.pause 📋Edge2/6/2025542
javascript.builtins.Atomics.waitAsync 📋Edge11/19/20202082
javascript.builtins.DataView.getFloat16 📋Firefox8/6/2024726
javascript.builtins.DataView.setFloat16 📋Firefox8/6/2024726
javascript.builtins.Error.Error.fileName_parameter Firefox11/9/20047936
javascript.builtins.Error.Error.lineNumber_parameter Firefox11/9/20047936
javascript.builtins.Error.columnNumber Firefox11/9/20047936
javascript.builtins.Error.fileName Firefox11/9/20047936
javascript.builtins.Error.lineNumber Firefox11/9/20047936
javascript.builtins.FinalizationRegistry.symbol_as_target Edge1/12/20231298
javascript.builtins.Float16Array 📋Firefox8/6/2024726
javascript.builtins.Float16Array.Float16Array 📋Firefox8/6/2024726
javascript.builtins.Function.displayName Firefox6/5/20125171
javascript.builtins.InternalError Firefox11/9/20047936
javascript.builtins.InternalError.InternalError Firefox11/9/20047936
javascript.builtins.Intl.DurationFormat 📋Edge9/19/2024682
javascript.builtins.Intl.DurationFormat.DurationFormat 📋Edge9/19/2024682
javascript.builtins.Intl.DurationFormat.format 📋Edge9/19/2024682
javascript.builtins.Intl.DurationFormat.formatToParts 📋Edge9/19/2024682
javascript.builtins.Intl.DurationFormat.resolvedOptions 📋Edge9/19/2024682
javascript.builtins.Intl.DurationFormat.supportedLocalesOf 📋Edge9/19/2024682
javascript.builtins.Intl.Locale.getCalendars 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getCollations 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getHourCycles 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getNumberingSystems 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getTextInfo 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Deno: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getTimeZones 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.Locale.getWeekInfo 📋Edge10/17/2024654
Chrome: Implemented as an accessor property.Chrome Android: Implemented as an accessor property.Edge: Implemented as an accessor property.Node.js: Implemented as an accessor property.Quest Browser: Implemented as an accessor property.Opera: Implemented as an accessor property.Opera Android: Implemented as an accessor property.Safari: Implemented as an accessor property.Safari on iOS: Implemented as an accessor property.Samsung Internet: Implemented as an accessor property.WebView Android: Implemented as an accessor property.WebView on iOS: Implemented as an accessor property.
javascript.builtins.Intl.PluralRules.PluralRules.options_parameter.options_roundingIncrement_parameter Firefox8/1/20231097
javascript.builtins.Intl.PluralRules.PluralRules.options_parameter.options_trailingZeroDisplay_parameter Firefox8/1/20231097
javascript.builtins.Math.f16round 📋Firefox8/6/2024726
javascript.builtins.Promise.incumbent_settings_object_tracking 📋Firefox11/15/20163547
javascript.builtins.RegExp.escape 📋Firefox1/7/2025572
javascript.builtins.Uint8Array.fromBase64 📋Firefox11/26/2024614
javascript.builtins.Uint8Array.fromHex 📋Firefox11/26/2024614
javascript.builtins.Uint8Array.setFromBase64 📋Firefox11/26/2024614
javascript.builtins.Uint8Array.setFromHex 📋Firefox11/26/2024614
javascript.builtins.Uint8Array.toBase64 📋Firefox11/26/2024614
javascript.builtins.Uint8Array.toHex 📋Firefox11/26/2024614
javascript.builtins.WeakMap.symbol_as_keys Edge1/12/20231298
javascript.builtins.WeakRef.symbol_as_target Edge1/12/20231298
javascript.builtins.WeakSet.symbol_as_keys Edge1/12/20231298
javascript.grammar.trailing_commas.trailing_commas_in_dynamic_import Edge5/27/20211893
Node.js: The second parameter no longer throws a parser error, but the --experimental-json-modules flag is still needed to load JSON modules.
javascript.operators.import.options_parameter Edge5/27/20211893
Node.js: The second parameter no longer throws a parser error, but the --experimental-json-modules flag is still needed to load JSON modules.
javascript.statements.import.import_attributes 📋Edge3/22/2024863
javascript.statements.import.import_attributes.type_css Edge3/22/2024863
javascript.statements.import.import_attributes.type_json Edge3/22/2024863
javascript.statements.import.service_worker_support Edge5/27/20211893
javascript.statements.import.worklet_support Firefox6/6/20231153