Is it possible to list all custom events created?

Question

I know it is possible to add an event listener to a custom event that I have created in Javascript, like this:

window.addEventListener("MyCustomEvent", myFunction, false);

But...Is it possible to list All custom events that exist at any point?

The above line adds an event listener regardless of whether the event exists or not, so I cannot indicate if the event exists or not.

Answer 1

This is generally a bad idea, but if you really have the need for this, you could override the addEventListener function like this to keep track of the events added:

var events = {};
var original = window.addEventListener;

window.addEventListener = function(type, listener, useCapture) {
    events[type] = true;
    return original(type, listener, useCapture);
};

function hasEventBeenAdded(type) {
    return type in events;
}

Keep in mind that this will only work for code that adds event listeners after this piece of code is included.