Perf: Use Set for O(1) source origin lookup - #3372
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Convert _sourceOrigins from array to Set to improve performance of message event validation. The indexOf() check was O(n), now has() is O(1). This is called on every postMessage event, so the improvement is significant in high-frequency messaging scenarios. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Improves performance of iframe event listener origin validation.
Issue
The _sourceOrigins array was checked using indexOf() on every postMessage event.
This is O(n) complexity, even though typically only 2 origins are checked.
Changes
Performance Impact
Testing
Note
Low Risk
Internal lookup change only; origin allowlist contents and validation logic stay the same.
Overview
Speeds up
postMessageorigin checks inIframeEventListenerby storing allowed origins in aSetand usinghas()instead ofindexOf()on an array.Allowed origins are still the parsed source origin and its
wwwvariant. Behavior and public API are unchanged.Reviewed by Cursor Bugbot for commit 6085fc9. Bugbot is set up for automated code reviews on this repo. Configure here.