How to write a FireFox UI-less addon without using XUL files

Question

I want to write a FireFox extension which simply loads myJavaScript.js if the user navigates to www.myExampleWebsite.com. Futhermore this page then detects that the plugin is installed and interacts with it (but this is not part of the question). I've heard of a possibility by creating an overlay (XUL), which does then define a script-tag with src="myJavaScript.js". In this file I check with progress listeners for the current URL. But this way feels kind of awkward.

My Question is now: How can I write a native (no special magic SDK) FF plugin without the need for defining a XUL file, but loading a JS file directly if the user navigates to a certain page (owned by me).

In chrome extensions such JS files can be defined directly in the manifest file by using the content_scripts key and the matches array like:

...

"content_scripts":
[{
    "matches": ["https://*.myExampleWebsite.com/*"],
    "js": ["myJavaScript.js"],
    "run_at": "document_idle"
}]

...

There must be an equivalent in FF for this. I searched and googled for 3 hours without any success.

Thank you in advance.

Answer 1

It's called bootstrap addon. Search my _ff-addon-template files at my gists on github:

https://gist.github.com/search?q=%40Noitidart+addon

You'll probably be interested in: _ff-addon-template-BootstrapWatchHostEventListenerInjectFiles.xpi

which watches sites load then do stuff with them on load. basic bootstrap skeleton: https://gist.github.com/Noitidart/9025999