OpenLayers 3: Remove event listener

Question

In Openlayers 3 how to remove a event listener attached like this:

var a = map.on("pointerdrag",function (e) {
             // event handler
});

var b = map.on("pointerdrag",function (e) {
             // event handler
});

How do I remove only listner a and keep b active?

Accepter

Answer 1

Ah its pretty simple! Its in the API Docs: unByKey, but very counter-intuitive name for an off function.

So to remove the event listener a:

map.unByKey(a);

Will remove a listener but keep the b on.

Note: this will work across any object in Open Layers 3 that emits an event. like Layers, Interactions etc..

Accepter

Note you can also use .un, if you are using a named function. function onPointerDragOne() {/*do stuf*/} function onPointerDragTwo() {/*do stuf*/} map.on("pointerdrag", onPointerDragOne); map.on("pointerdrag", onPointerDragTwo); map.un("pointerdrag", onPointerDragOne); // Only onPointerDragTwo will run – Pathoneurosis

Answer 2

I was just wondering the same thing, seems like off would be the appropriate method to remove an event listener. You can also call this directly in the event callback:

map.on("pointerdrag", function (e) {
    map.unByKey(e);
});

This should remove only the this specific event.

Intelligible

Why I'll do such thing? – Erythroblastosis