Firefox

4 items

Web

Safari 27 fixes top-level await, after WebKit rewrote the module loader in C++

WebKit published the fix on September 2, 2026. Dynamic imports of a module that uses top-level await could complete out of order in Safari, and an importer that ran early hit an error about accessing a value before initialization. The cause was a module loader built on the abandoned WHATWG Loader proposal rather than on the algorithms in the ECMAScript standard. WebKit rewrote the loader from self-hosted JavaScript into native C++, and the result ships in Safari 27 and in Safari Technology Preview 251.

WebKitSeptember 3verified

Web

Firefox will ship JPEG XL, and the decoder had to be rewritten in Rust first

Mozilla posted its intent to ship on August 24. The condition it set five years ago was met: Google Research rebuilt the decoder in Rust, because 100,000 lines of multithreaded C++ was too much attack surface to accept.

Mozilla HacksAugust 25verified

Web

Firefox 154 brings sibling-index(), sibling-count(), and text-box-trim

The August 18 release adds three CSS features you can use right away. sibling-index() and sibling-count() give an element's position among its siblings and their total, directly in CSS and without a line of JavaScript, which ends the need to hand-write variables like --i for staggered animation delays. Alongside them come text-box-edge, text-box-trim, and the text-box shorthand, which remove the extra space above and below text so headings finally sit in the grid the way they look in the design. On the JavaScript side, includes(), join(), chunks(), and windows() were added to the iterator prototype.

MDNAugust 20verified

Web

New on the web platform in July: Firefox 153 and Chrome 151

Rachel Andrew summarizes July's stable releases, and one item outweighs the rest: Firefox 153 widened how the select element is parsed, so any nested element is allowed inside it. That opens the path to genuinely customizable dropdowns without a JavaScript replacement, which is the most troublesome category of hand-built component on client sites. The same release brings the Picture-in-Picture API to desktop, the Intl.Locale Info API with getCalendars(), getTimeZones(), and getWeekInfo(), and IndexedDB getAllRecords(). Chrome 151 adds the CSS ruby-overhang property, manual slot assignment in declarative Shadow DOM through the shadowrootslotassignment attribute, and the animation property on the AnimationEvent and TransitionEvent interfaces.

web.devAugust 20verified