When using alert(), confirm() or onbeforeunload, Chromium's old behavior was to block JS waiting for the result, but allows all declarative animations to continue. This change is to make all main-thread tasks (such as <marquee> and CSS 2d animations) also pause during this interval.

Demo

Specification

Established standard

Status in Chromium

Blink


Enabled by default (tracking bug) in:

  • Chrome for desktop release 52
  • Chrome for Android release 52
  • Android WebView release 52

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • No signal
  • No signal
  • Shipped/Shipping
  • No signals

Owners

Comments

Chrome’s old behavior was implemented with a nested message loop on the Blink main thread. Any code that might ever run on a nested message loop must be robust to reentrancy and reordering, otherwise there will be stability and security bugs.

Last updated on 2020-11-09