Is it possible to inject JavaScript into a web-page with the help of a browser extension and guarantee that the page cannot override it? If this is not possible can the extension somehow check if its injected JavaScript is not used or something?
I want to deliver a JavaScript library over a safe channel, but I don't want it on a webserver.
Sounds like a job for chrome extensions. There you'll have a way called "Content Scripts". I hope thats that what youre looking for!