topic Finding map extent for javascript api and spatial reference in ArcGIS JavaScript Maps SDK Questions

Finding map extent for javascript api and spatial reference

yockee — Thu, 16 Jan 2025 03:26:04 GMT

I am having trouble in finding map extent (bounding box). How can I easily find out the extent and its format ?

Suppose I have this code sample:

const view = new MapView({ container: "viewDiv", map: map, extent: { // autocasts as new Extent() xmin: -9177811, ymin: 4247000, xmax: -9176791, ymax: 4247784, spatialReference: 102100

I want to direct the extent (xmin/max, ymin/max) to a particular city with spatial reference 102100. How to do that ?

And also, spatialReference 102100 (line 11) is deprecated and changed to EPSG 3857. (https://spatialreference.org/ref/esri/102100/) . Do I have to change the "spatialReference: 102100" to "spatialReference: 3857" ?

Thanks

Re: Finding map extent for javascript api and spatial reference

JamesIng — Mon, 20 Jan 2025 23:23:48 GMT

You can add a `console.log` to output the view.extent.

If you add it inside a reactiveUtils.watch you can get it to output to the browser console as you move around the map to the city / extent that you want.

reactiveUtils.watch( () => view.updating, (updating) => { console.log('extent', view.extent) });

If you want the map itself to goto an extent, then you can use `goTo` and pass in a geometry that matches your extent (or use Polygon.fromExtent to convert it)

https://developers.arcgis.com/javascript/latest/api-reference/esri-geometry-Polygon.html#fromExtent

https://developers.arcgis.com/javascript/latest/api-reference/esri-views-MapView.html#goTo