How to detect HTTP status from JavaScript

Question

I want to detect in a script, which could be deployed beyond my control, whether the page was delivered with a HTTP status of 200, 404 or 500 etc.

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Answer 1

Why does the javascript need to know this? Sounds like it would make more sense just to embed it on a custom 404 page. No need to detect HTTP status of the parent page (I don't think it's possible - maybe doing an ajax call to itself after each load, but that's just silly). if the code is being executed, its guaranteed to be a 404