code: function(className, callback) {
          var self = this,
              cs = className.split(' ');
          return this.length && (function() {
                  var hasIt = true;
                  self.each(function(el) {
                    cs.forEach(function(clazz) {
                      if (hasClass(el, clazz)) {
                          if (callback) callback(el);
                      } else hasIt = false;
                    });
                  });
                  return hasIt;
              })();
      }
docs: hasClass
  --------
  
  Checks if the class is on _all_ elements in the xui collection.
  
  ### syntax ###
  
  x$( selector ).hasClass( className, fn );
  
  ### arguments ###
  
  - className `String` is the name of the CSS class to find.
  - fn `Function` is a called for each element found and passed the element _(optional)_.
  
  `element` is the HTMLElement that has the class
  function(element) {
  console.log(element);
  }
  
  ### example ###
  <div id="foo" class="foo awesome"></div>
  <div class="foo awesome"></div>
  <div class="foo"></div>
  
  returns true
  x$('#foo').hasClass('awesome');
  
  returns false (not all elements with class 'foo' have class 'awesome'),
  but the callback gets invoked with the elements that did match the 'awesome' class
  x$('.foo').hasClass('awesome', function(element) {
  console.log('Hey, I found: ' + element + ' with class "awesome"');
  });
  
  returns true (all DIV elements have the 'foo' class)
  x$('div').hasClass('foo');