AgPad is a small, fast and powerful freeware general purpose text editor. Currently this application supports code completion for JavaScript and syntax highlighting for many languages.
SplineTech JavaScript Debugger PRO is an award-winning javascript debugging tool that enables you to easily edit and debug JavaScript and JQuery events. Client-Side JavaScript, JScript, JQuery, MS CRM and ExtJS debugging fully supported.
It is powerful editor for JavaScript, XUL/XBL, Laszlo, Flex, SVG, Silverlight and Yahoo! Widget development. The JavaScript editor provides features like code completion and content outline that helps developers productively create JavaScript code.