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Starred by 8 users

Issue metadata

Status: WontFix
Owner:
Closed: Oct 2017
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 3
Type: Bug



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Fast-downloading defered scripts seem to block rendering/parsing

Project Member Reported by jakearchibald@chromium.org, May 3 2017

Issue description

https://cdn.rawgit.com/jakearchibald/1e503f1689adbbc8f62b74d20cdefe42/raw/61ad816d1da35e2aecc5f0a0729920da3bb8f653/

Run a timeline while loading the above. The effect may only be visible with a full cache.

According to devtools, the deferred script appears to block parsing, but this isn't what deferred scripts are supposed to do. Is this devtools misreporting, or is it really blocking parsing?

Also, it seems to block rendering, which is surprising, but I remember pmeenan@ mentioning this may depend on the elements that come before it.
 
Profile-20170503T141938.json
2.1 MB View Download
Owner: a...@chromium.org

Comment 2 by a...@chromium.org, Oct 6 2017

Status: WontFix (was: Untriaged)
Works fine for me. I modified the HMTL to be:

<div style="width:100px;height:100px;background:green"></div>
<script defer src="1.js"></script>
<script src="2.js"></script>

And timeline shows that 1.js is parsed at the very end, after 2.js. Closing as non-repro.

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