Google extension to load specific elements on page using proxy

Hello,

I want a google chrome OR mozilla firefox extention that will use a proxy with (username+password+portnumber) to load specific elements on the page visited.

Sample: Use proxy to load .JS (javasript) code lines only.

If the JS file loads an image then it should stop using the proxy. Use proxy only for javascript requests.

This is to avoid using proxy to load images or videos.

Thanks