topic Can you use dojo on.once() with map::update-end event? in ArcGIS JavaScript Maps SDK Questions

Can you use dojo on.once() with map::update-end event?

JerryGarcia — Tue, 31 Jan 2017 19:56:23 GMT

If so, can someone provide example code?

Thanks!

Re: Can you use dojo on.once() with map::update-end event?

thejuskambi — Sat, 11 Dec 2021 13:34:44 GMT

Hello Jerry,

I am not able to understand the objective of a example. on.once is a method in dojo, used to listen to an event only once. it would be similar to code below.

var handle = on(map, "click", function(evt){
   ...
   handle.remove();
}‍‍‍‍

It does not matter, which event. you can use on.once on any event, which you would like to listen just once.

Re: Can you use dojo on.once() with map::update-end event?

JerryGarcia — Tue, 31 Jan 2017 22:39:22 GMT

Thanks. But, it is not always that simple... I want my code to fire only once. I have a couple callbacks when the event occurs. So... I need to wait until the callbacks are finished or, I was thinking, use the nifty on.once dojo functionality. I'm still not clear how to invoke it's magic.

None of the following works:

on.once(...);

on(...).once();

handle.once();

Re: Can you use dojo on.once() with map::update-end event?

RobertScheitlin__GISP — Sat, 11 Dec 2021 13:34:47 GMT

Jerry,

I use dojo on.once quit often in code.

on.once(map, "update-end", function(){
    // will only fire once...
});‍‍‍‍‍‍

Re: Can you use dojo on.once() with map::update-end event?

JerryGarcia — Wed, 01 Feb 2017 01:20:48 GMT

I see. Pretty simple. Thanks!

Re: Can you use dojo on.once() with map::update-end event?

Anonymous User — Sat, 11 Dec 2021 13:34:50 GMT

This works as long as the dojo.on module is called first, like so:

require(["dojo/on"],
function(on) {
on.once(map, "update-end", function(){
    // will only fire once...
});
});

Thanks for this great tip!