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Result
Method
The pattern runs in a disposable local Web Worker. The worker is terminated after 300 milliseconds to reduce the risk of a pathological pattern blocking the page. Results are rendered as inert text.
Limits and assumptions
Patterns are limited to 500 characters and test text to 1 MB. JavaScript regular-expression syntax and flags apply. A timeout is a practical browser safeguard, not proof that a pattern is efficient or safe in every application.