Do you know of a bleeding-edge HTML5 leveraging, legacy-ignoring JavaScript framework?

What's the best framework (sort of jquery, extjs, etc like) to use if I'd like to intensively use all the freshest technologies of the HTML5 stack provided by modern browsers (Firefox 7, Safari 5, Chrome 14) and have absolutely no need to support any legacy browsers (incl. no need in IE support at all and no need in Firefox or Chrome prior to the latest stable releases)? I'd like to get all the newest available goodness without having (even abstracted by a library layer) a line of code meant just fore legacy compatibility or keeping any legacy-induced things in mind.

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.
  

What does ExtJS ComboBox triggerAction: "all” really do?

I tried to create a simple ComboBox:

var combo1 = new Ext.form.ComboBox({

  store: [1,2,3],

  renderTo: document.body

});

ExtJS grab JSON result

I'm generating JSON response from PHP witch looks like this:

{ done:'1', options: [{ message:'Example message'},{message:'This is the 2nd example message'}]}

Ext JS 4.0 providing "unconventional” data to charts

I have a store which always contains a single record. Lets say the record looks like this: