Web extension boilerplate files for web application testers.
This is a near minimum code base for creating your own web extension.
This code is unsigned, so you can't load it like a normal web extension. Unless you are using a development version of a browser, you have to install it temporarily. Restarting the browser will require you to re-load the plugin.
The src/manifest.json file registers a content script src/script.js. The
content script will run in every frame, at page load. The content script gets
it's own scope but shares the DOM with the web page. So it adds JavaScript to
the DOM of the web page. The added JavaScript shares the scope of the web page
and will execute first.
As a proof of concept, the script augments the functionality of
document.write with a console.log of arguments.
// example code to dump all arguments to document.write
document.write = new Proxy(document.write, {
apply: function(_func, _doc, args) {
console.group(`[**] document.write.apply arguments`);
for (const arg of args) {
console.dir(arg);
}
console.groupEnd();
return Reflect.apply(...arguments);
}
});Replace that code with what ever you want and it will run first in all frames.