diagnostic · one of 29free, no counter
Mutations
What is this page rewriting after it has loaded?
A page that flickers, re-renders or loses a form value is doing something after load, and the browser has no surface that shows what. This is a running observer with a ledger behind it: which elements are being rewritten, how often, and by how much - with the busiest row as the scale, because a share of the total draws every quiet row as nothing.
Reach itPress ⌘+K on any tab and type mutations.Ctrl+Kon Windows and Linux
TWO BUILDS9 browsers
Chromelisting in reviewFirefoxlisting in reviewBravelisting in reviewOperalisting in reviewEdgelisting in review4 moreChromium browsers: Arc, Vivaldi, Chromium, Opera GXthe Chrome buildin the panel · free, no counter
What this actually is
what the page rewrites after load, liveOn a flicker nobody can reproduce, on a page whose input keeps being reset, and on any site where a third-party script is suspected of rewriting content. Leave it running and use the page.
Asked about this diagnostic
4 of themWhy is there no Run again?
Because it is a running observer with a log behind it. Re-running would throw the log away, and the log is the reading.
It reports mutations on a page that looks static. Is that wrong?
Usually not. Analytics scripts, lazy-loading, font swapping and animation libraries all rewrite the DOM. The rate and the shares are how you tell background noise from a re-render loop.
Does it say which script did it?
No. A mutation record names what changed, not who changed it - the browser does not attribute them. What it gives you is the element, which is usually enough to find the owner.
Does watching slow the page down?
A `MutationObserver` is cheap, but a page doing thousands of mutations a second will feel the ledger. That page has a problem the ledger is there to show you.
TWO BUILDS9 browsers
Chromelisting in reviewFirefoxlisting in reviewBravelisting in reviewOperalisting in reviewEdgelisting in review4 moreChromium browsers: Arc, Vivaldi, Chromium, Opera GXthe Chrome build63 of these · no host permissions · three free audits