Bug 261655

Summary:

script type="module" doesn't wait for CSS

Product:

WebKit

Reporter:

Rene Haas <king-sora>

Component:

Page Loading

Assignee:

Nobody <webkit-unassigned>

Status:

NEW

Severity:

Normal

CC:

beidson, cdumez, karlcow, webkit-bug-importer, ysuzuki

Priority:

Keywords:

BrowserCompat, InRadar

Version:

Safari 17

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Minimal reproducable example	none

Rene Haas

Reported 2023-09-17 10:43:59 PDT

Created attachment 467721 [details] Minimal reproducable example When using a script with `type="module"` I would expect the script to be deferred until CSS is parsed and executed. (same behavior as with the `defer` attribute) In webkit this doesn't happen. I've attached a minimal example. Open it in browsers such as Firefox or Chrome and the result will be always the same: The `div` element will always have its color (red / rgb(255, 0, 0)) as its text. In WebKit / Safari this won't be always the case (to reproduce it consistently disable cache in the network devtools). The example looks like this: ===================== index.html: ===================== <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <link rel="stylesheet" href="styles.css" /> </head> <body> <div></div> <script type="module"> document.querySelector('div').innerHTML = getComputedStyle(document.querySelector('div')).backgroundColor; </script> </body> </html> ===================== styles.css ===================== div { width: 200px; height: 200px; background: red; } One important note to make here is that if I switch out `type="module"` with `defer` everything works as expected.

Attachments
Minimal reproducable example (570 bytes, application/x-zip-compressed) 2023-09-17 10:43 PDT, Rene Haas	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2023-09-24 10:44:12 PDT

<rdar://problem/115961182>

Rene Haas

Comment 2 2025-10-01 10:16:28 PDT

Any updates?..

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