Barry Pollard

The unload event will be gradually deprecated by gradually changing the default so that unload handlers stop firing on pages unless a page explicitly opts in to re-enable them. Deprecation timeline We noted that unload behavior would likely be subject to changes as early as January 2019, when we announced our intent to implement a back/forward cache. In parallel to the implementation work, we conducted a large outreach which resulted in a significant drop of unload usage.

The Long Animation Frames API (LoAF - pronounced Lo-Af) is a new proposal from the Chrome team to update the Long Tasks API to provide a better understanding of slow user interface (UI) updates. This can be useful to identify slow animation frames which are likely to affect the pending Interaction to Next Paint (INP) Core Web Vital metric which measures responsiveness, or to identify other UI jank which affects smoothness.

Speculation rules can be used to prefetch and prerender next page navigations as detailed in the previous blog post. This can allow for much quicker—or even instant—page loads, greatly improving Core Web Vitals for these additional page navigations. Debugging speculation rules can be tricky. This is particularly true for prerendered pages, as these pages are rendered in a separate renderer—kind of like a hidden background tab that replaces the current tab when activated.