Is it necessary/advisable to check if an eventHandler exists before trying to remove it?

Question

I've got something like this:

if (something) {
    init();
} else {
    document.addEventListener('CUSTOM_EVENT', init, false);
}

var init = function() {
    document.removeEventListener('CUSTOM_EVENT', init, false);
    // do stuff
}

Do I need to add some kind of check around that removeEventListener call? If so, I could do:

var eventAdded = false;
if (something) {
    init();
} else {
    document.addEventListener('CUSTOM_EVENT', init, false);
    eventAdded = true;
}

var init = function() {
    if (eventAdded) {
        document.removeEventListener('CUSTOM_EVENT', init, false);
    }
    // do stuff
}

but that feels a bit inelegant. I'd rather just leave the raw removeEventListener call if that's no big deal, or do something that doesn't require having an external var if possible.

Answer 1

https://developer.mozilla.org/en/DOM/element.removeEventListener

Calling removeEventListener() with arguments which do not identify any currently registered EventListener on the EventTarget has no effect.