Three20-chrome-extension is a project mainly written in JavaScript, it's free.
A Google Chrome Extension to search the Three20 API Docs
This very simple extension adds an 'tt' command to the Chrome Omnibox. For example, typing 'tt TTView' will bring up a list of all class names in the Three20 Library API matching 'TTView'—selecting a list item navigates to the relevant Three20 API Reference URL on api.three20.info.
Install through the Google Chrome Extension Gallery
———————— Requires Chrome 9 or later.
This is inspired by Roman Nurik's Android SDK Reference Search and The Google Chrome Extensions sample: Extension Docs Search.