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 FirefoxNot in Safari
In Firefox 37
In Safari 23

Unstable APIs

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

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.waitAsync 📋Safari3/27/20231224
javascript.builtins.Error.Error.fileName_parameter Firefox11/9/20047936
javascript.builtins.Error.Error.lineNumber_parameter Firefox11/9/20047936
javascript.builtins.Error.cause.displayed_in_console Firefox8/10/20211818
javascript.builtins.Error.columnNumber Firefox11/9/20047936
javascript.builtins.Error.fileName Firefox11/9/20047936
javascript.builtins.Error.lineNumber Firefox11/9/20047936
javascript.builtins.Error.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serialized properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 adds serialization of stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 adds serialization of stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serialized properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 adds serialization of stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 adds serialization of stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.EvalError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.FinalizationRegistry.symbol_as_target Safari3/27/20231224
javascript.builtins.Function.displayName Firefox6/5/20125171
javascript.builtins.InternalError Firefox11/9/20047936
javascript.builtins.InternalError.InternalError Firefox11/9/20047936
javascript.builtins.Intl.DurationFormat 📋Safari3/27/20231224
javascript.builtins.Intl.DurationFormat.DurationFormat 📋Safari3/27/20231224
javascript.builtins.Intl.DurationFormat.format 📋Safari3/27/20231224
javascript.builtins.Intl.DurationFormat.formatToParts 📋Safari3/27/20231224
javascript.builtins.Intl.DurationFormat.resolvedOptions 📋Safari3/27/20231224
javascript.builtins.Intl.DurationFormat.supportedLocalesOf 📋Safari3/27/20231224
javascript.builtins.Intl.Locale.getCalendars 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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 📋Safari9/18/20231049
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_trailingZeroDisplay_parameter Firefox8/1/20231097
javascript.builtins.Iterator.Iterator 📋Firefox10/1/2024670
javascript.builtins.Iterator.drop 📋Firefox10/1/2024670
javascript.builtins.Iterator.every 📋Firefox10/1/2024670
javascript.builtins.Iterator.filter 📋Firefox10/1/2024670
javascript.builtins.Iterator.find 📋Firefox10/1/2024670
javascript.builtins.Iterator.flatMap 📋Firefox10/1/2024670
javascript.builtins.Iterator.forEach 📋Firefox10/1/2024670
javascript.builtins.Iterator.from 📋Firefox10/1/2024670
javascript.builtins.Iterator.map 📋Firefox10/1/2024670
javascript.builtins.Iterator.reduce 📋Firefox10/1/2024670
javascript.builtins.Iterator.some 📋Firefox10/1/2024670
javascript.builtins.Iterator.take 📋Firefox10/1/2024670
javascript.builtins.Iterator.toArray 📋Firefox10/1/2024670
javascript.builtins.JSON.isRawJSON 📋Firefox2/4/2025544
javascript.builtins.JSON.parse.reviver_parameter_context_argument 📋Firefox2/4/2025544
javascript.builtins.JSON.rawJSON 📋Firefox2/4/2025544
javascript.builtins.Promise.incumbent_settings_object_tracking 📋Firefox11/15/20163547
javascript.builtins.RangeError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.ReferenceError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.SyntaxError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.TypeError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.URIError.serializable_object 📋Firefox7/26/20221468
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.WeakMap.symbol_as_keys Safari3/27/20231224
javascript.builtins.WeakRef.symbol_as_target Safari3/27/20231224
javascript.builtins.WeakSet.symbol_as_keys Safari3/27/20231224
javascript.grammar.trailing_commas.trailing_commas_in_dynamic_import Safari9/20/20211777
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 Safari9/20/20211777
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.regular_expressions.modifier 📋Firefox10/29/2024642
javascript.statements.import.import_attributes 📋Safari12/11/2023965
javascript.statements.import.import_attributes.type_json Safari12/11/2023965
javascript.statements.import.service_worker_support Safari9/20/20211777
javascript.statements.import.worklet_support Firefox6/6/20231153