JavaScript editor within Eclipse [closed]
Eclipse HTML Editor Plugin
I too have struggled with this totally obvious question. It seemed crazy that this wasn't an extremely easy-to-find feature with all the web development happening in Eclipse these days.
I was very turned off by Aptana because of how bloated it is, and the fact that it starts up a local web server (by default on port 8000) everytime you start Eclipse and you can't disable this functionality. Adobe's port of JSEclipse is now a 400Mb plugin, which is equally insane.
However, I just found a super-lightweight JavaScript editor called Eclipse HTML Editor Plugin, made by Amateras, which was exactly what I was looking for.
Disclaimer, I work at Aptana. I would point out there are some nice features for JS that you might not get so easily elsewhere. One is plugin-level integration of JS libraries that provide CodeAssist, samples, snippets and easy inclusion of the libraries files into your project; we provide the plugins for many of the more commonly used libraries, including YUI, jQuery, Prototype, dojo and EXT JS.
Second, we have a server-side JavaScript engine called Jaxer that not only lets you run any of your JS code on the server but adds file, database and networking functionality so that you don't have to use a scripting language but can write the entire app in JS.
Try the Vjet Javascript IDE from ebay (installation)
Ganymede's version of WTP includes a revamped Javascript editor that's worth a try. The key version numbers are Eclipse 3.4 and WTP 3.0. See http://live.eclipse.org/node/569
There once existed a plugin called JSEclipse that Adobe has subsequently sucked up and killed by making it available only by purchasing and installing FlexBuilder 3 (please someone prove me wrong). I found it to worked excellent but have since lost it since "upgrading" from Eclipse 3.4 to 3.4.1.
The feature I liked most was Content Outline.
In the Outline window of your Eclipse Screen, JSEclipse lists all classes in the currently opened file. It provides an overview of the class hierarchy and also method and property names. The outline makes heavy use of the code completion engine to find out more about how the code is structured. By clicking on the function entry in the list the cursor will be taken to the function declaration helping you navigate faster in long files with lots of class and method definitions