1580536 - Dynamic module import generates an error at parse time in contexts where it is not supported

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Jon Coppeard (:jonco)]

Currently use of dynamic import causes a syntax error at parse time in web workers. Bug 1540913 comment 6 suggests that it would be more useful for this to fail at runtime as it would make it easier to provide a fallback for web worker scripts when run in FF.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1580536 - Make dynamic import a runtime error in contexts where we don't support it r?jorendorff

This removes the parse-time check for whether dynamic import hook has been set. There's already a runtime check for this too, previously just to support enabling/disabling dynamic import via a pref. I updated web platform tests and expectations so that use of dynamic imports in wokers is now an expected failure (previously we would time out).

Comment 2

[tobiasuhlig78]

It would be very much appreciated to get the fix to replace the parse time with a run time check into FF.

I am creating a new web worker driven UI framework and this error is a big show stopper.
I had to replace several JS modules with copies (if possible), just to exclude unreachable code from FF.

In general: adding support for JS modules & dynamic imports inside the worker scope should get a high priority,
since this is a direction UI app development is moving towards to.

Thx & best regards
Tobi

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/31e9cee63560
Make dynamic import a runtime error in contexts where we don't support it r=jorendorff

Comment 4

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/19678 for changes under testing/web-platform/tests

Comment 5

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

Comment 6

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/31e9cee63560

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/mozilla-central/rev/8aa8bbbf0bee
Add back test annotations lost during merge conflict. a=permafail-fix,test-only