return false, preventDefault, and stopPropagation in jQuery

return false, preventDefault, and stopPropagation in jQuery - return false equals to 'preventDefault + stopPropagation' - stopImmedidatePropagation is 'stopPropagation' and will cancel the event handlers applies to the target

$('a').click( function(event) {
  return false;
});

is equivalent to

$('a').click( function(event) {
  event.preventDefault();
  event.stopPropagation();
});

demo: http://css-tricks.com/examples/ReturnFalse/

  // http://www.w3.org/TR/2003/WD-DOM-Level-3-Events-20030331/ecma-script-binding.html
  jQuery.Event.prototype = {
    preventDefault: function() {
      this.isDefaultPrevented = returnTrue;

      var e = this.originalEvent;
      if (!e) {
        return;
      }

      // if preventDefault exists run it on the original event
      if (e.preventDefault) {
        e.preventDefault();

        // otherwise set the returnValue property of the original event to false (IE)
      } else {
        e.returnValue = false;
      }
    },
    stopPropagation: function() {
      this.isPropagationStopped = returnTrue;

      var e = this.originalEvent;
      if (!e) {
        return;
      }
      // if stopPropagation exists run it on the original event
      if (e.stopPropagation) {
        e.stopPropagation();
      }
      // otherwise set the cancelBubble property of the original event to true (IE)
      e.cancelBubble = true;
    },
    stopImmediatePropagation: function() {
      this.isImmediatePropagationStopped = returnTrue;
      this.stopPropagation();
    },
    isDefaultPrevented: returnFalse,
    isPropagationStopped: returnFalse,
    isImmediatePropagationStopped: returnFalse
  };

  // Run delegates first; they may want to stop propagation beneath us
      for (i = 0; i < handlerQueue.length && !event.isPropagationStopped(); i++) {
        matched = handlerQueue[i];
        event.currentTarget = matched.elem;

        for (j = 0; j < matched.matches.length && !event.isImmediatePropagationStopped(); j++) {
          handleObj = matched.matches[j];

          // Triggered event must either 1) be non-exclusive and have no namespace, or
          // 2) have namespace(s) a subset or equal to those in the bound event (both can have no namespace).
          if (run_all || (!event.namespace && !handleObj.namespace) || event.namespace_re && event.namespace_re.test(handleObj.namespace)) {

            event.data = handleObj.data;
            event.handleObj = handleObj;

            ret = ((jQuery.event.special[handleObj.origType] || {}).handle || handleObj.handler).apply(matched.elem, args);

            if (ret !== undefined) {
              event.result = ret;
              if (ret === false) {
                event.preventDefault();
                event.stopPropagation();
              }
            }
          }
        }
      }