Any subsitute for extent-change in Arcgis Javascript 4?

[ADITYAKUMAR1]

Hi ,

  I was working on Arcgis Javascript 3 with the below code.

on(this.map, "extent-change", lang.hitch(this, this.myfunction));

The above line called myfunction during load of the map .But now I am working with ArcGIS JavaScript 4. Any idea how to replicate the same in version 4?

[JoelBennett]

When migrating to 4.x, I found it best to replace this by watching the MapView.stationary property, in which case yours would translate to something like:

mapView.watch("stationary", this.myFunction.bind(this));

and elsewhere, something like:

myFunction: function(newValue, oldValue, propertyName, target) {
	if (newValue) {
		var extent = target.extent;

		//etc
	}
}

[ADITYAKUMAR1 · Accepted solution]

Hi @JoelBennett , @Noah-Sager 

   Thanks for the response. I managed to do it in a different way.

map.View.watch("zoom", (evt) => {
if (Number.isInteger(evt)) {
this.myfunction();
}
});

Its working for now but this doesnt work when we work with custom base maps.I am not sure why it only works with default basemap gallery.

Thanks

Aditya Kumar

[JoelBennett]

The 3.x "extent-change" event will fire when the user pans the map, but your 4.x solution will not.  Is that what you intend?

[ADITYAKUMAR1]

@JoelBennett no not on extent change but on scale change Or a change in zoom level. 

[Noah-Sager]

Also, here are some good example apps related to extent changes from the SDK:

https://developers.arcgis.com/javascript/latest/sample-code/watch-for-changes-reactiveutils/

https://developers.arcgis.com/javascript/latest/sample-code/event-explorer/

https://developers.arcgis.com/javascript/latest/sample-code/watch-for-changes/