There are times when a web designer will have to emulate a desktop program for the web. There are many tools written in javascript which can help web designers create consistent user interfaces for the web. Designing web elements and letting the browser determine how it should look may be okay for some projects but for products where branding is important additional help is required to keep the look consistent regardless of the web browser used.

Here are 21+ javascript based web Graphic User Interface tools which can help design consistent UI elements across different browsers. *Javascript must be enabled on the user's browser for these to work.

For Desktop Browsers

1.  AmpleSDK

Ample SDK is a standard-based cross-browser JavaScript GUI Framework for building Rich Internet Applications. It employs XML technologies (such as XUL, SVG or HTML5) for UI layout, CSS for UI style and JavaScript for application logic. It equalizes browsers and brings technologies support to those missing any.

2.  ExtJS

Ext JS is a JavaScript platform for rapid development of cross-browser web apps. Ext JS helps you build sustainable applications faster than ever.

3.  DHTMLX

dhtmlxLayout is a JavaScript DHTML component that provides powerful and efficient solution for building Ajax-enabled web interfaces with ease. This component allows you to programmatically define interface structure, including layout of elements and their sizes. End users can easily resize interface elements, collapse or expand them.

4.  Ajax.org

Ajax.org Platform is a pure javascript application framework for creating real-time collaborative applications that run in the browser.

5.  jQuery UI

jQuery UI provides abstractions for low-level interaction and animation, advanced effects and high-level, themeable widgets, built on top of the jQuery JavaScript Library, that you can use to build highly interactive web applications.

6.  YUI Library

YUI is a library of JavaScript utilities and controls for building richly interactive web applications using techniques such as DOM Scripting, DHTML, and Ajax. It is available under a BSD license and is free for all uses.

7.  MochaUI

MochaUI is a web applications user interface library built on the Mootools JavaScript framework.

8.  Jitsu

Jitsu contains an integrated set of tools to enable developers to build and deploy sophisticated user interfaces for web applications.

9.  Livepipe

LivePipe UI is a suite of high quality widgets and controls for web 2.0 applications built using the Prototype JavaScript Framework. Each control is well tested, highly extensible, fully documented and degrades gracefully for non JavaScript enabled browsers where possible.

10.  Echo

Echo is an open-source framework for developing rich web applications. From the developer's perspective, Echo behaves as a user interface toolkit--like Swing or Eclipse SWT.

11.  Sigma Widgets

Sigmasoft Technologies LLC is a software company providing cross-browser javascript GUI components and tools & services involved. Our aim is to make AJAX simple and easy.

12.  Spry

Spry is a JavaScript-based framework that enables the rapid development of Ajax-powered web pages.

13.  Qooxdoo

qooxdoo is a comprehensive and innovative framework for creating rich internet applications (RIAs). Leveraging object-oriented JavaScript allows developers to build impressive cross-browser applications.

14.  jQuery Tools

jQuery Tools is a collection of the most important user-interface components for today's websites. This single JavaScript file weighs only 5.72 Kb

For Mobile Browsers

15.  IUI

iUI is a framework consisting of a JavaScript library, CSS, and images for developing iPhone webapps.

16.  iWebkit

Iwebkit is the revolutionnairy kit used to create high quality iPhone and iPod touch websites in a few minutes and is based on an LGPL license.

17.  iPhone Universal

The UiUIKit (Universal iPhone UI Kit) it's a collection of HTML examples of what can be done with CSS3 and Safari's Webkit.

18.  jQTouch

A jQuery plugin for mobile web development on the iPhone, iPod Touch, and other forward-thinking devices.

19.  WebApp.net

WebApp.Net is a light weight, powerful javascript framework taking advantage of AJAX technology. It provides a full set of ready to use components to help you develop, quickly and easily, advanced mobile web applications.

20.  PhoneGap

PhoneGap is an open source development tool for building fast, easy mobile apps with JavaScript.

21.  Mobify

Mobify is a free service that makes WordPress, Drupal and other websites mobile-friendly. Supports iPhone, Android, BlackBerry and 5000+ other devices.

Bonus

22.  124+ Ajax Framework and Javascript Libraries

Do you currently use any of these frameworks in your web design projects? If not, which ones do you use? Your comments are appreciated.