Which JavaScript framework (jQuery vs Dojo vs … )?

There are a few JavaScript frameworks/toolsets out there, such as:

• 
  jQuery ;
  


• 
  Dojo ;
  


• 
  Prototype ;
  


• 
  YUI ;
  


• 
  MooTools ;
  


• 
  ExtJS ;
  


• 
  SmartClient ;
  


• 
  Zepto and
  


• others I'm sure.
  

jQuery / Dojo - How do I use jQuery with Dojo toolkit

How do I use jQuery with Dojo toolkit? I've heard of both libraries being used simultaneously, jQuery for DOM-related and Dojo for UI (dijit), but I can't find any tutorials or examples of this. Will I run into any conflicts or issues if I load both libraries?

Dojo require() and AMD (1.7)

I'm having a heckuva time transitioning to Dojo and the new AMD structure, and I'm really hoping someone can shed some light on the whole concept. I've been living on Google for the last few weeks trying to find information on not the usage, but the structure and design pattern trends in using this.

file upload using dojo.io.frame.send doesn't work in IE the first time

I'm trying to do an ajax file upload using dojo.io.frame.send(). It works with FF and chrome without any issues but not in IE 8 (not sure about other versions). The code is pasted below: