Recs.
Updated
SpecsUpdate
Pros
Pro Free and cross-platform
NetBeans is a free, GPL-licensed IDE. It can can run on any computer with a Java virtual machine. If a computer has a Java virtual machine (JVM), Netbeans can run on it. Netbeans can therefore run on a variety of operating systems such as Windows, *nix, and Mac OS.
Pro Autocompletes your code
Code auto-completion is of great help in agile development environments, where you're pumping out a new version as soon as possible. In such environments you need your IDE to be "as fast as you code", hence Netbeans can be of great assistance in such situations. The IDE will auto-complete your code (variable names / function references / library functions / classes / ids) wherever possible, so you can code at speed.
Cons
Con Needs some setup to work with Javascript
Netbeans needs to be properly set up to work with Javascript. In the end it provides autocompletion and documentation for external libraries including your own libraries.