JavaScript dynamically changes the onclick event

The first type: Button.onclick = Function ("alert (' Hello ');");

The second type: Button.onclick = function() {alert ("Hello");};

The Third Kind: Button.onclick = Myalert;

function Myalert () {
Alert ("Hello");
}

The fourth type:

This situation is more dynamic, more practical, and can add multiple functions (the order in which the events are added is the order of execution), hehe
    if (window.addeventlistener) {//Mozilla , Netscape, Firefox
        //element.addeventlistener (Type,listener, Usecapture);
        button.addeventlistener (' Click ', alert (' One '), false);
        button.addeventlistener (' Click ', alert (' n '), false);// Execution order
    } else {//IE
         Button.attachevent (' onclick ', function () {alert (' 21 ');});
        button.attachevent (' onclick ', function () {alert (' 22 ');}); Execution order
    }

Example Explanation:
Button.onclick = Function ("alert (' 31 ');");
Button.onclick = Function ("alert (' 32 ');");
Button.onclick = Function ("alert (' 33 ');"); If this is the case, then only the last method will be executed.

Button.attachevent ("onclick", function () {alert (' 41 ');});
Button.attachevent ("onclick", function () {alert (' 42 ');});
Button.attachevent ("onclick", function () {alert (' 43 ');}); If this is the case, three methods will be executed.

Of course, you can write that too.
Button.onclick = Function ("alert (' 51 ');");
Button.attachevent ("onclick", function () {alert (' 52 ');});

Corresponding removal events
DetachEvent (' onclick ', func);//ie using Delete event func
RemoveEventListener (' click ', func);//mozilla, delete event func

JavaScript dynamically changes the onclick event