Prototype takes the complexity out of client-side web programming. Built to solve real-world problems, it adds useful extensions to the browser scripting environment and provides elegant APIs around the clumsy interfaces of Ajax and the Document Object Model.
Dojo Toolkit saves you time and scales with your development process, using web standards as its platform. It’s the toolkit experienced developers turn to for building high quality desktop and mobile web applications. From simple websites to large packaged enterprise applications whether desktop or mobile, Dojo will meet your needs.
Sencha Ext JS is the industry’s most powerful desktop application development platform with unparalleled cross-browser compatibility, advanced MVC architecture, plugin-free charting, and modern UI widgets.
Backbone.JS should appear in these list.