found this cool little trick in page builder to find closing bracket/parenthesis/braces --> CTR + P

We use the ACE Editor in the Skuid builder. It comes with lots of cool keyboard shortcuts and tricks.  Here is their documentation. 

Hi Pat,

We just use Ace Editor in Skuid, so here’s a list of the hotkeys.

https://github.com/ajaxorg/ace/wiki/Default-Keyboard-Shortcuts

Getting autocomplete to work correctly for a loosely typed language like Javascript actually might be pretty difficult.  (Although I’m sure someone out there has done it.)  Here are the options that I’ve used to write Javascript in Static Resources for Salesforce.

1. Eclipse with Force.com IDE
This is the setup I currently use exclusively. Pros: Works well when working with teams.  Prevents overwriting static resources that were changed by another developer. Has everything eclipse has to offer.  Plugins that I currently use (and love) are the Eclipse JSHint plugin and the ZipEditor Plugin for Eclipse.
I prefer to install the standard version of Eclipse (I’m currently running the Luna version of Eclipse IDE for Java EE Developers) and then install the Force.com IDE after that.

2. Sublime Text with Mavens Mate
Sublime Text is my favorite text/code editor.  Mavens Mate seems to work pretty well.  We at Skuid mostly abandoned this because it didn’t handle conflict resolution with Static Resources very well at the time.  I’m not sure if it’s been improved since I worked with it.

3. Salesforce Developer Console
This has always been kind of buggy and annoying, but they have been improving it with every release.

The browser (I use Chrome) Javascript console is your best friend for testing.