The application scenario of event bubbling and event capture--event agent/event delegate

Use the event agent to bind the click event for all a tags in the page.

Document.addeventlistener ("click", Function (e) {
	if (E.target.nodename = = "a")
		Console.log ("a");
FALSE);

Problem: If the a tag still has span, IMG and other elements, in the above code, click Span, IMG and other elements can not trigger the Click event.

Reason: When you click on other elements such as span, IMG, and so on, e.target points to the element that triggers the Click event (Span, IMG, and other elements) instead of a label.

Workaround: Start with the element that triggers the Click event, and look up until you find the A label.

Document.addeventlistener ("click", Function (e) {
	var node = e.target;
	while (Node.parentNode.nodeName!= "Body") {
		if (Node.nodename = = "a") {
			console.log ("a");
			break;
		node = Node.parentnode;
	}
}, False);