Why can't I use addEventListener to stop contextmenu event?

Question

I want to prohibit the right mouse button. But I find that if I write this:

document.addEventListener('contextmenu', function(event) {
    return false;
}, false);

It will not work, the event will still work.

But if I write it like this,

document.oncontextmenu = function() {
    return false;
}

The right mouse button will not work.

I wish to know why I can't use addEventListener to stop the event contextmenu.

Answer 1

As stated in "Preventing the Browser's Default Action", the return of false value is not enough for preventing default action. You need to call preventDefault() method on Event object:

document.addEventListener('contextmenu', function(event) {
   event.preventDefault();
}, true); 

DEMO