Cosmetic Filters -- "+js(...)"

[nitishk1-hub]

Can you help with an example to trigger alert when ever i visit example.com

and also what othere thigs possible using this filters

[seia-soto]

Hi @nitishk1-hub ,

Sorry but it's not clear what you want to achieve. Our adblocker library is the universal library could be reused dynamically on various platforms like browsers, playwright, electron, and puppeteer.

For the cosmetic filters including the following pattern: +js(name, arg1, arg2, arg3, ...) are called scriptlets. It executes a registered code snippet called name with args (arg1, arg2, arg3, ...).

You'll need to take care of FiltersEngine.resources to make it work.

Best

[nitishk1-hub]

@seia-soto

{
"name": "popads.js",
"aliases": [
"popads.net.js",
"prevent-popads-net.js"
],
"body": "(function(){"use strict";const n=String.fromCharCode(Date.now()%26+97)+Math.floor(Math.random()*982451653+982451653).toString(36);const o=window.onerror;window.onerror=function(e,t,r,i,d){if(typeof e==="string"&&e.indexOf(n)!==-1)return true;if(o instanceof Function)return o(e,t,r,i,d)}.bind();const e=function(){throw new ReferenceError(n)};delete window.PopAds;delete window.popns;Object.defineProperties(window,{PopAds:{set:e},popns:{set:e}})})();",
"contentType": "application/javascript"
},

TO execute this scriptlet do we need to create a custon filter??

like testing-site-28nf.onrender.com##+js(popads.js)??

Or how can i observe where or if the scriptlets are been executed?

[seia-soto]

Yes, you need a filter.

Unfortunately, there's no built-in way to confirm if a specific scriptlet has been executed in the website or not. However, we provide an event listener interface on FiltersEngine. Please, reference to this file location: https://github.com/ghostery/adblocker/blob/master/packages/adblocker/src/engine/engine.ts#L111.

Moreover, if your needs is to execute a script in puppeter just like userscripts, it might be easier to use puppeter api directly.

I hope this helped and have awesome weekend.

[nitishk1-hub]

@seia-soto
testing-site-28nf.onrender.com##+js(popads.js)?? is this custom filter usage is right ??

For running below scriplets??

{
"name": "popads.js",
"aliases": [
"popads.net.js",
"prevent-popads-net.js"
],
"body": "(function(){"use strict";const n=String.fromCharCode(Date.now()%26+97)+Math.floor(Math.random()*982451653+982451653).toString(36);const o=window.onerror;window.onerror=function(e,t,r,i,d){if(typeof e==="string"&&e.indexOf(n)!==-1)return true;if(o instanceof Function)return o(e,t,r,i,d)}.bind();const e=function(){throw new ReferenceError(n)};delete window.PopAds;delete window.popns;Object.defineProperties(window,{PopAds:{set:e},popns:{set:e}})})();",
"contentType": "application/javascript"
},

The website testing-site-28nf.onrender.com contains a network call to https://testing-site-28nf.onrender.com/popads.js

So if my understanding is right The original file should be replaced with the scriptlet function.

Correct me if i am wrong and also if filter is incorrect.

Also is there a way to check as a test by triggering an alert("working") using scriptlet on visiting 'example.com' Is yes please help with the way of creating a sample scriptlets and how to add or integrte it to the extension.

[nitishk1-hub]

@seia-soto any update??

[seia-soto]

The custom filter usage is right but it doesn't work like that. We just execute the corresponding script in the website context. If you want to replace a network request, you need to create a redirect filter instead.

Unfortunately, there's no additional layer to check if script has executed or not in the context. You'll need to touch the scriptlet or preload script to do that. When doing that, you need to watch where actually you're running the code: electron backend or frontend.