1504682 - <link rel=preload as=script> + <script> with same URL trigger duplicate HTTP requests

Status: RESOLVED DUPLICATE of bug 1393540

(Core :: Networking: HTTP, defect)

Description

[jakub.g]

Attachment: preload-before-script.html

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.30 Safari/537.36

Steps to reproduce:

1. Go to `about:config`, enable `network.preload` flag. 
2. Open devtools, go to Network panel, toggle "disable cache"
3. Load https://jg-testpage.github.io/wpt/preload-before-script.html
4. Load https://jg-testpage.github.io/wpt/preload-after-script.html


Actual results:

In both [3] and [4], all 3 URLs that are used through <script> and <link rel=preload as=script> are loaded from network twice


Expected results:

In both cases, they should be loaded from network only once.

Comment 1

[jakub.g]

Cross-browser compat tests:

- Chrome not affected
- Safari not affected
- Edge is affected by [4] but not by [3]. 

I opened https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/19471670/ for Edge.

Comment 2

[jakub.g]

FWIW the same happens also for same-origin scripts:

https://jg-testpage.github.io/wpt/preload-before-script-sameorigin.html

Comment 3

[Dragana Damjanovic [:dragana]]

rel-preload implementation is not complete.