How do inject a script into a website *before* the first script on this website is able to run?
manuel.reimer at gmx.de
Tue Aug 15 12:52:37 UTC 2017
before Firefox 55 I was able to do the following:
Register my content script to run at "document_start".
Then I was able to access "document.head" from there and inject my
<script> as the very first script to load.
I need my script to run right in website context as my script is meant
impossible with a content script directly.
Since Firefox 55 it seems to be impossible to do so. "document_start"
seems to fire before "<head>" even exists.
I tried to fix this with the "DOMContentLoaded" but this now is too
late. Scripts embedded into <body> already ran at this point...
Then I tried a "MutationObserver" to maybe wait for the point when
<head> is inserted, but for me the MutationObserver is never fired.
Can someone please point me into the right direction?
Thanks in advance
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