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Synchronous XMLHttpRequest on the main thread is deprecated
See original GitHub issueWhen running less.js in Chrome Canary (39.0.2171.95) I get a warning in the console
Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check http://xhr.spec.whatwg.org/.
We are running into the same problem in Firefox and IE: there is a big FOUC while less is downloading files.
Is there a way to prevent this ? I understand the rationale of the deprecation, but for devs, it’s still needed…
Issue Analytics
- State:
- Created 9 years ago
- Comments:13 (6 by maintainers)
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@nitriques This is already released. “async” is no longer applied to the XHR request. Instead, it controls whether the page displays before or after the style sheet is created.
I’ve fixed this issue pretty much exactly the way I suggested. Just needs code review for merging.
Btw, for me, changing the sync XHR to a “fake sync” (preventing FOUC) changed the render time for my stylesheets from 7-10 seconds to somewhere around a second. So, quite an improvement.