Set custom extent in ArcGIS JSAPI 3.4/3.5

Question

I am using ESRI suit 10.1 and ArcGIS JSAPI 3.4/3.5.

I want to set custom extent (for India) for this map and trying to assign the coordinate in center but its not getting proper map.

In previous version (3.0/3.1) we used dojo.toJson(map.extent.toJson()); with the help of firebug to identify the extent of the specific area(x min,y min, x max,y max) then we used that extent for base map.

What I tried :

-I checked the API reference but I did not get any information.

-Is there any Dojo problem (might be few references gets updated?)

-Tried to use lat,lon values at Center property but not getting perfect map for India

In new version I am not getting this so is there any way to identify the custom extent using previous tool and use those in center property ?

Any help will be great !!!

Answer 1

I'm not sure why you cannot get the extent of an existing map, but I can use console.dir(map.extent.toJson()); to get the extent, for example on this map: http://developers.arcgis.com/en/javascript/samples/widget_overviewmap/

My usual way of solving this issue, is first creating an extent from lat-long (i.e. WGS84), and then projecting it to the map's projection.

If your maps projection is in WebMercator, then you can use the following function from the geometry class: esri.geometry.geographicToWebMercator(geometry)

Once you have the extent in the map's coordinate system, you can set the extent of the map in the constructor.

The following code works:

function init() {
    var gcsExtent = new esri.geometry.Extent(65,10,100,35, new esri.SpatialReference({wkid: 4326}));  
    var WMextent= esri.geometry.geographicToWebMercator(gcsExtent);

    var map = new esri.Map("map",{
                    basemap:"topo",
                    extent: WMextent,
                    sliderStyle:"small"
                    });
}

I have also updated your jsfiddle: http://jsfiddle.net/cn5eV/3/

Answer 2

Below are the link to the example to find the extent of the map frame.I have Modified your example to set extent rather then using center I have set Extent. Usually ESRI using 102100 projection than 4326.Extent Example. I have used this forum link onExtentChange. I have written the function that will write value of extent in console log for more help.