ASSIGNED193616
Web Inspector: Make completion popover faster by removing setInterval 
https://bugs.webkit.org/show_bug.cgi?id=193616
Summary Web Inspector: Make completion popover faster by removing setInterval
Nikita Vasilyev
Reported 2019-01-19 18:09:08 PST
CompletionSuggestionsView.prototype.hideWhenElementMoves calls getBoundingClientRect() every 0.2 seconds. getBoundingClientRect isn't terribly expensive: console.time("getBoundingClientRect"); let clientRect = element.getBoundingClientRect(); console.timeEnd("getBoundingClientRect"); It was between 0.02ms and 0.07ms when adding a new property to <body> on webkit.org. If it's possible, we should use IntersectionObserver instead.
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Nikita Vasilyev
Comment 1 2019-04-05 18:39:56 PDT
Unfortunately, I don't see how IntersectionObserver can be helpful here. "The Intersection Observer API provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element" - because one element has to be an ancestor of another, I don't see how it to make it work here. --- There're libraries in the wild to detect resize events without timeouts. Perhaps it's worth investigating what they do. http://marcj.github.io/css-element-queries/
Radar WebKit Bug Importer
Comment 2 2019-04-05 18:45:21 PDT
<rdar://problem/49664005>
Nikita Vasilyev
Comment 3 2019-04-05 19:00:49 PDT
The following cases need to be handled: 1. One of the parent elements scrolled. Solution: listen "scroll" on every parent. 2. One of the parent elements resized. Solution: use ResizeObserver on every parent. 3. One of the parent elements resized becomes invisible or gets detached from DOM. This happens when tab or sidebar panel changed. Solution: Mutation Observers? This is quite a lot of events and observers. I'm not sure it's worth it.
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