Newish Firefox Features
#71 · 2025-07-29 · Firefox- Revamped Profile UI
- Tab Groups
- Vertical Tabs
- Translations
- Multi-Account Containers
- uBlock Origin
Collection of interesting bits and bytes about the Web. Mostly short and to the point.
ECMAScript 2025 has been released.
The following proposals have reached Stage 4 and are part of ECMAScript 2025:
Iterator.from()Iterator.prototype.drop()Iterator.prototype.every()Iterator.prototype.filter()Iterator.prototype.find()Iterator.prototype.flatMap()Iterator.prototype.forEach()Iterator.prototype.map()Iterator.prototype.reduce()Iterator.prototype.some()Iterator.prototype.take()Iterator.prototype.toArray()Promise.try
Math.f16round
RegExp.escape
Most of these new features have already landed in all the important browser engines. Check their compatibility before using them.
What about Temporal? It is still on Stage 3 and thus not part of ECMAScript 2025. There is currently only one conforming implementation (Spidermonkey, released in Firefox 139), but the ECMAScript process requires at least two conforming implementations in order to reach Stage 4. Temporal will likely be part of ECMAScript 2026.
Temporal has shipped in Firefox 139.
Thank you, André!
Interop 2025 is a cross-browser effort to improve the interoperability of the web — to reach a state where each technology works exactly the same in every browser.
Resources:
Announcements by contributors:
Temporal is an ECMAScript proposal to add new date and time APIs to JavaScript.
It has been in the making for a long time by now. The proposal's repository appeared in 2017 and a lot of activity happened within the last four years. One topic that took a while was the IETF standardization of string formats used in zone annotations. But that has been completed at the end of 2023.
In mid 2024, a scope reduction was discussed at the meetings of TC39. Apparently, some implementors have reservations about the proposal's size and complexity. As a result, some parts of the proposal were removed and may be added in future proposals instead.
But now, finally, it looks like we may soon see Temporal within browsers and other JavaScript engines. Until recently, implementors were not allowed to ship Temporal implementations without hiding them behind a flag. But that restriction was removed from Temporal's README in January. And in the July meeting of TC39, it was noted that Temporal implementations may ship unflagged. Even better, the work-in-progress implementations of Temporal in SpiderMonkey (Firefox), V8 (Chrome), and JavaScriptCore (Safari) already pass many of the required feature tests.
One remaining open issue is the final normative specification text for ECMAScript Temporal, though. But we may already see first implementations and polyfills hopefully soon. Thanks to everybody involved in the process!