handle/listen Layer visibility events

[davizuco666]

I need to listen to layer visibility changes, but can´t figure out how to do it with Javascript 4.x SDK.

LayerList "trigger-action" never triggers on layer visibility changes.

I Tryed like:LayerList.on

But just working on "load" event..

Also triyed to see all events to find the right one, with no success.

Any ideas?

[davizuco666 · Accepted solution]

Auto awnser:

layer.watch('visible', (visibility, a, eventName,layer) => {
                console.log("visible: ", visibility);
                console.log(layer, eventName, a);
            });

I don't understand why there is no mention of this in the documentation, watch is not even in the list of methods.

You just have to guess...

[KenBuja]

Have you seen this section in the Programming patterns page that discusses watching for property changes?

[davizuco666]

No I didn´t 😅, it was quite hidden. 🤔  Thank you for the link! 😜

[LaurenBoyd]

@davizuco666 there is also a sample that shows how to take advantage of reactiveUtils and watch for when the map's layer visibility changes: https://developers.arcgis.com/javascript/latest/sample-code/watch-for-changes-reactiveutils/ 

It is recommended to use reactiveUtils - here's a blog that discusses the topic more: https://www.esri.com/arcgis-blog/products/js-api-arcgis/developers/reactiveutils-and-why-you-should-...