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Dynamic imports loaded as low-priority scripts when compiled #6980

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wbinnssmith opened this issue Sep 23, 2021 · 0 comments · Fixed by #7061
Closed

Dynamic imports loaded as low-priority scripts when compiled #6980

wbinnssmith opened this issue Sep 23, 2021 · 0 comments · Fixed by #7061
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🐛 Bug Good First Issue ✨ Parcel 2

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@wbinnssmith
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wbinnssmith commented Sep 23, 2021 •
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Native dynamic imports (e.g. import('./foo')) are typically loaded by browsers with high priority. However, when targeting browsers without native or polyfillable support, Parcel inserts <script async> tags into the head, which are loaded with low priority. See https://addyosmani.com/blog/script-priorities/.

With that said, we should probably still include the async attribuite on these scripts as their execution order isn't important. One workaround to boost priority of async scripts is to also insert a <link rel="preload" as="script"> with an href with the same value as the script's src.

We should consider adding these link tags as well when loading js targeted at these environments.

Related: #6981
@wbinnssmith wbinnssmith mentioned this issue Sep 23, 2021
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highvoltag3 added a commit to highvoltag3/parcel that referenced this issue Oct 4, 2021
@highvoltag3
Dynamic imports loaded as low-priority scripts when compiled, fixes p…
59a61fa 
…arcel-bundler#6980
@highvoltag3 highvoltag3 mentioned this issue Oct 13, 2021
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devongovett pushed a commit that referenced this issue Mar 20, 2022
@highvoltag3
Dynamic imports priority fix closes #6980 (#7061)
c394019
gorakong pushed a commit that referenced this issue Nov 3, 2022
@lettertwo
Merge v2 into lettertwo/v2-2022-03-24
2b39275 
* upstream/v2:
  Upgrade Flow to 0.174.1 (#7849)
  v2.4.0
  v2.4.0 changelog
  Bump Parcel CSS
  Dynamic imports priority fix closes #6980 (#7061)
  fix(transformers): errors.map is not a function (#7672)
  Make NodeResolver check realpath before resolving with `source` entry (#7846)
  docs: fix wrong location documents (#7689)
  Fix: escape double quote of url value in CSS `url()` (#7718)
  Update @parcel/css and add diagnostic for url dependencies in custom properties (#7845)
  Use relative path for bundle labels in bundle analysis (#7737)
  Allow use react-jsx transform in React 16.14.0 (#7728)
  Move to @parcel/css by default (#7821)
  Feature: pick PORT number also from .env file (#7819)
  Enable parsing static initialization blocks (#7839)
  Bump swc and prevent pure comment removal (#7833)
  Bump swc (#7777)
  Human readable file size in bundle analyzer report (#7766)
  Improve emoji support detection (#7775)
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Dynamic imports priority fix closes #6980 highvoltag3/parcel
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@wbinnssmith @mischnic