Changing style of VectorTileLayer causes data to be fetched

[RyanSutcliffe]

A colleague pointed out that, when you change the style for a VectorTileLayer in the JavaScript Maps SDK, the browser goes and fetches tiles of data for that layer.

You can see/reproduce this behavior when looking at the CodePen example  posted  by  @UndralBatsukh in an earlier thread in this forum.

clicking a feature to change style causes fetches to server

Is this to be expected? Is it possibly a bug?

I was about to implement this behavior with a "mouseover" event. This would cause it to fire quite frequently as the user moves their cursor around over various features (even with some debouce handling). I wasn't expecting it to initiate any data fetches because it is just changing the color of an existing layer style.

[I can reproduce behavior running latest 4.31 version of the API].

[UndralBatsukh · Accepted solution]

Hi there, 

This is expected behavior. When calling setStyleLayer, even if it modifies an existing layer—or adds a new one—the layer may have a different query or layout. As a result, we need to access the PBF (protocol buffer) and reprocess the features to ensure they align with the updated configuration. We fetch pbf for visible tiles.

[RyanSutcliffe]

Ah interesting thanks. I didn't think that queries or styling changes on the frontend would affect what was being fetched over the wire from the VectorTileServer. I figured it fetched everything as raw data and then drew what was needed according to whatever filters and/or styling rules were present on the ESRI layers.