World_Topo_Map initialExtent Error

Question

I'm finally getting around to learning the ArcGIS API for JavaScript and seem to run into a bug. It seems that the World_Topo_Map service will not take an initialExtent without erroring out to 0,0 (Lat/Lon). But the ESRI_StreetMap_World_2D works fine.

Comment/uncomment to toggle the layers. If someone could confirm that I'm not going insane and my code is correct, it would be greatly appreciated. TIA -Tom

derekswingley1 · Answer

Additionally, if you want to use a wkid:4326 extent to specify the extent for a map in web mercator (wkid:102100), there is a helper method to convert between the two:  esri.geometry.geographicToWebMercator.

Also check out the Working with Extents help topic in the conceptual help.

SiqiLi · Answer

Hi Tom, 
In your code, you specify the spatial reference used for the map extent is 4326. Since ESRI_StreetMap_World_2D map service uses SR 4326, your code is fine with that map service.  However World_Topo_Map uses 102100, That's why your code doesn't work.

To solve the issue, please modify the definition of your spatial reference and map extent as follows:  var spatialRef = new esri.SpatialReference({wkid:102100});
        var startExtent = new esri.geometry.Extent();
        startExtent.xmin = -14133053.98 ;
        startExtent.ymin = 3198163.32;
        startExtent.xmax = -11931667.56;
        startExtent.ymax = 4665754.26;
        startExtent.spatialReference = spatialRef;

If you want to get the information about extent, please check the following sample:
http://help.arcgis.com/en/webapi/javascript/arcgis/demos/map/map_currentextent.html