progress events will no longer be fired for sync XHR in workers

Published: | Categories: DOM

Description

Starting with Firefox 63, the progress events will no longer be fired for synchronous requests within workers, according to the latest XMLHttpRequest spec. On the main thread, this type of event hasn’t been fired at least since Firefox 52. If you’d like to monitor progress on download or upload, you have to use an asynchronous request which is not affected by this change.

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