removeEventListener without knowing the function

Question

Some of the third party plugin will attach the eventListener into the site. How to I remove the eventListener without knowing the function that attached.

Answer 1

getEventListeners(window) will return a map of events and their registered event listeners.

So for DOMContentLoaded event for example you can have many event listeners. If you know the index of the listener you want to remove (or if there exists only one), you can do:

var eventlistener = getEventListeners(window)["DOMContentLoaded"][index];
window.removeEventListener("DOMContentLoaded", 
                           eventlistener.listener,
                           eventlistener.useCapture);