How to create a bookmarklet with an external js file.

bookmarklet.js

// use this code as your href attribute on your 'Install this bookmarklet' anchor tag.
// borrowed from http://net.tutsplus.com/tutorials/javascript-ajax/create-bookmarklets-the-right-way/

javascript:(function(){var jsCode = document.createElement('script');jsCode.setAttribute('src', 'http://example.com/path/to/file.js');document.body.appendChild(jsCode);}());