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feat: Add content script noScriptStartedPostMessage option#2265

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aklinker1 merged 3 commits into
wxt-dev:mainfrom
jviney:add-content-script-noScriptStartedPostMessage-option
May 11, 2026
Merged

feat: Add content script noScriptStartedPostMessage option#2265
aklinker1 merged 3 commits into
wxt-dev:mainfrom
jviney:add-content-script-noScriptStartedPostMessage-option

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@jviney
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@jviney jviney commented Apr 14, 2026

Overview

The deprecated window.postMessage path for the wxt:content-script-started message causes bad interactions with sites that have a poorly implemented event listener. Eg a previously dormant event listener like this is now triggered to become an infinite loop of message passing:

window.addEventListener("message", (event) => {
  event.source.postMessage("something")
})

This PR adds an option to exclude the window.postMessage event entirely, until such time as WXT completely removes it, which is a breaking change.

There are two recent PRs that discuss the move away from window.postMessage to custom events.
#1938
#2035

Manual Testing

Checked the postMessage is no longer sent to the window.

Simple reproduction of the issue:

<!DOCTYPE html>
<html lang="en">
<head>
    <script>
      window.addEventListener("message", (e) => {
        console.log("GOT MESSAGE", e, e.detail)
        e.source.postMessage("Hello from the message handler!", "*")
      })
    </script>
    <title>Hello World</title>
</head>
<body>
    <h1>Hello, World!</h1>
</body>
</html>

@jviney jviney requested a review from aklinker1 as a code owner April 14, 2026 00:40
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@github-actions github-actions Bot added the pkg/wxt Includes changes to the `packages/wxt` directory label Apr 14, 2026
@jviney
Add content script noScriptStartedPostMessage option.
280df61 
The deprecated `window.postMessage` path for the `wxt:content-script-started` message causes bad interactions with sites that have a poorly implemented event listener.

This PR adds an option to exclude the `window.postMessage` event entirely, until such time as WXT completely removes it, which is a breaking change.

Related PRs
wxt-dev#1938
wxt-dev#2035
@jviney jviney force-pushed the add-content-script-noScriptStartedPostMessage-option branch from 4319253 to 280df61 Compare April 14, 2026 00:40
@wooly
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wooly commented May 11, 2026

Tiny bump on this one if you've got some free time, @aklinker1

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aklinker1 commented May 11, 2026

Thanks for the ping! We'll get this merged and released today.

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pkg-pr-new Bot commented May 11, 2026 •
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@wxt-dev/analytics

npm i https://pkg.pr.new/@wxt-dev/analytics@2265

@wxt-dev/auto-icons

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@wxt-dev/browser

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@wxt-dev/i18n

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@wxt-dev/is-background

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commit: 2de4b23

aklinker1
aklinker1 reviewed May 11, 2026
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Comment thread packages/wxt/src/types.ts Outdated
@aklinker1 aklinker1 changed the title Add content script noScriptStartedPostMessage option. feat: Add content script noScriptStartedPostMessage option May 11, 2026
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codecov Bot commented May 11, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.41%. Comparing base (a0a2394) to head (2de4b23).

Additional details and impacted files 
@@            Coverage Diff             @@
##             main    #2265      +/-   ##
==========================================
- Coverage   78.53%   78.41%   -0.13%     
==========================================
  Files         133      133              
  Lines        3876     3877       +1     
  Branches      870      871       +1     
==========================================
- Hits         3044     3040       -4     
- Misses        746      749       +3     
- Partials       86       88       +2

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@aklinker1 aklinker1 enabled auto-merge (squash) May 11, 2026 12:17
@aklinker1 aklinker1 merged commit f771e6a into wxt-dev:main May 11, 2026
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github-actions Bot commented May 11, 2026

Thanks for helping make WXT better!

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@aklinker1 aklinker1 aklinker1 approved these changes

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@jviney @wooly @aklinker1