How to modify web content using apache proxy?

I'm using apache server to test my browser开发者_StackOverflow社区. I want to insert some javascript to a web page, such as google.com to analyze the page content.

Other debugging methods are limited by my browser to use. So I want to modify the page contents at the proxy end.

Tank you very much!

Squid is a solid web proxy with easy hooks for modifying pages on the fly. You can start with this and change the script and hooks to modify html instead of images.