#Chrome Extension Messaging Sample

The JavaScript components of Chrome extensions have several restrictions due to cross-origin policy. This sample extension serves as boilerplate code for first-timers.

Comedy of restrictions:

• background.js runs independent of tabs.
• content.js is tab-specific.
• Only background.js can make web requests.
• Only content.js can access DOM of the page.
• iframe.js can neither access DOM nor make web requests.
• background.js cannot see iframe.js and must talk to it through the content script that injected it.

background.js, iframe.js, and content scripts must rely on each other using message passing for functions they cannot perform.

popup.js works like a content script.

Here's a working example of an extension made that uses iframes: Claw4Twitter, source