A brief discussion on the principle of jQuery event binding_jquery

win.gevent = {
handle : function(event){
          var all, handlers;
//Packaging event
          event = arguments[0] = gevent.fix( event || window.event );
         event.currentTarget = this;
​​​​ //Here...
        var namespaces = event.type.split(".");
         event.type = namespaces.shift();
         all = !namespaces.length;
var namespace = RegExp("(^|\.)" namespaces.slice().sort().join(".*\.") "(\.|$)");
//Get the event list of the behavior of this element
            handlers = (data(this, "events") || {} )[event.type]; //Traverse this event list and execute the things to be executed
for ( var j in handlers ) {
            var handler = handlers[j];
If ( all || namespace.test(handler.type) ) {
                                  // Pass in a reference to the handler function itself
                              // So that we can later remove it
                             // The comment on jq is written like this. Reference the event handler to this event for convenience and remove it later
                                                // But in the remove, the event handler is not used. I don’t know what the use is here. And when there are multiple events, this event is replaced
                  event.handler = handler;
//Execute the event and it is an event called with an element. You can execute this element in the event and ret is the return value of the function
              var ret = handler.apply(this, arguments);
//If there is a return value and the return value is false, the execution prevents the event from bubbling and the default behavior of the execution event is blocked If( ret !== undefined ){
                     event.result = ret;
If ( ret === false ) {
                         event.preventDefault();
                           event.stopPropagation();
                 }
                                                                                                                                                                                                            }
},
props: "altKey attrChange attrName bubbles button cancelable charCode clientX clientY ctrlKey currentTarget data detail eventPhase fromElement handler keyCode metaKey newValue originalTarget pageX pageY prevValue relatedNode relatedTarget screenX screenY shiftKey srcElement target toElement view wheelDelta which".split(" "),   Fix : function(event){
//new setEvent will give the event an expando attribute. If there are any of the attributes, it means that the event has been generated and there is no need to wrap the event again
            if ( event[expando] )
            return event;
//Keep an original event
// new A new event. This is different from the original event
        var originalEvent = event;
        event = new setEvent(originalEvent);
//Get the attribute value of the original event. For what attribute values ​​there are, see this.props
for ( var i = this.props.length, prop; i; ){
              prop = this.props[ --i ];
            event[ prop ] = originalEvent[ prop ];
}
//Unify the target elements into event.target
If ( !event.target )
                event.target = event.srcElement || document; // Fixes #1925 where srcElement might not be defined either
//If it is found to be a text node, get its parent node
If ( event.target.nodeType == 3 )
             event.target = event.target.parentNode;
                             
If ( !event.relatedTarget && event.fromElement )
event.relatedTarget = event.fromElement == event.target ? event.toElement : event.fromElement;         return event;
                                             }
win.setEvent = function(src){
// Allow instantiation without the 'new' keyword
// Event object
If( src && src.type ){
This.originalEvent = src;
This.type = src.type;
// Event type
}else
This.type = src;
// timeStamp is buggy for some events on Firefox(#3843)
// So we won't rely on the native value
This.timeStamp = now();
// Mark it as fixed
This[expando] = true;
}
function returnFalse(){
Return false;
}
function returnTrue(){
return true;
}
setEvent.prototype = {
preventDefault: function() {
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)
e.returnValue = false;
},
stopPropagation: function() {
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();
},
isImmediatePropagationStopped: returnFalse
};