If you are already using Eclipse now you have to add to your toolbox JSEclipse, the new eclipse plugin for JavaScript development. JSEclipse helps developers code JavaScript faster and with no errors, you can complete a variety of tasks, from editing small sections of code to working with the next big AJAX library or developing plug-ins for a product that embeds JavaScript snippets. If you don't have eclipse yet, maybe it's time to give it a try and for PHP developers you might also check the Eclipse PHP Development Tool. JSEclipse features announced in this release :

• Contextual code completion & shortcuts.
• Project outline and quick navigation through function declarations.
• Syntax highlighting.
• Error reporting.
• Customizable code templates to get you started.
• Support for popular JavaScript libraries (Dojo, Prototype, YUI, Qooxdoo).
• Support for JavaDoc documentation and multi-line comments.