The unload event stops firing by default for 60% of page loads in Edge 152, 100% by Edge 155, so move telemetry and state-saving to pagehide or visibilitychange before your data silently vanishes.
Edge 152 starts phasing out the unload event. From this release, unload handlers stop firing by default for 60% of page loads, climbing to 80% in Edge 154 and 100% in Edge 155. Sites can opt back in through the new unload Permission-Policy, but that is a stay-of-execution, not a fix.
If your telemetry, analytics, or state-saving rides on unload, migrate it to pagehide or visibilitychange now. The handlers do not error when they stop running. They just never fire, and the data quietly vanishes. Chromium is retiring unload across the board, so this is not an Edge-only quirk you can wait out.
The release also adds media pseudo-classes (:playing, :paused, :seeking, :buffering, :stalled, :muted, :volume-locked), which let a custom player style its playback state without a class-toggling JS loop. ShadowRoot referenceTarget is the other keeper: it forwards ID references like label[for] and aria-labelledby across shadow boundaries, so forms and a11y keep working when you shadow-encapsulate a component.
Everything else is safe to skim. alpha() and window-drag, both CSS, are the niche ones here; file them away. The unload migration is the one with a deadline.
Edge 153 withholds `unload` handlers on 60% of page loads and climbs to 100% by Edge 155, while Chrome reaches those same shares on different milestones.
2 sources
Solid 2.0's release candidate reworks async around promises and new Loading/Errored/Reveal primitives while retiring SolidStart, so adopters need a migration plan before the stable release.
1 source
Microsoft Edge 151 swaps its legacy C++ XML parser for a Rust implementation, eliminating memory-corruption bugs in DOMParser and SVG parsing. Also ships CSS alpha() and Shadow DOM reference targets.
1 source