topic Re: FeatureLayer 'update-start' fires once when in visible scale range in ArcGIS JavaScript Maps SDK Questions

FeatureLayer 'update-start' fires once when in visible scale range

Anonymous User — Mon, 24 Aug 2015 17:58:30 GMT

Hi -

I have a FeatureLayer in a map that starts zoomed outside of its visible scale range. The first time the layer comes into its visible range, the 'update-start' event is triggered. Every time thereafter, an 'update' event is triggered (deprecated, I know). Never again does the layer coming in or out of scale trigger 'update-start', therefore I assumed it was firing that first time because the layer was being added to the map.

However, the map 'layer-add' event for this layer does not fire when the layer comes into its visible scale the first time. That event fires when the map initially loads on the screen, and the layer is out of visible scale.

Any input on what is triggering the event?

Re: FeatureLayer 'update-start' fires once when in visible scale range

TimWitt2 — Mon, 24 Aug 2015 18:02:46 GMT

Sarah,

in what mode (onDemand, Snapshot...) do you add your layer?

Tim

Re: FeatureLayer 'update-start' fires once when in visible scale range

Anonymous User — Mon, 24 Aug 2015 18:03:46 GMT

Snapshot

Re: FeatureLayer 'update-start' fires once when in visible scale range

TimWitt2 — Mon, 24 Aug 2015 18:12:16 GMT

Maybe because the first time it actually draws the layer, it queries the server, which counts as a refresh. Once it has been drawn the layer information remains in the cache and doesn't need to query the server and therefor doesn't "refresh", which would fire the update-start event?

It's just an idea

Re: FeatureLayer 'update-start' fires once when in visible scale range

Anonymous User — Mon, 24 Aug 2015 18:23:27 GMT

Hm, yes, that's a good point!