How do I get full URL from ArcGISDynamicMapServiceLayer

[ThomasRoussell]

If I set a dynamic layer like this

myLayer = new esri.layers.ArcGISDynamicMapServiceLayer("http://myserver:6080/ArcGIS/rest/services/MyLayers/MapServer", {id: "road_backlayer"});

it returns a url of:
"http://myserver:6080/ArcGIS/rest/services/MyLayers/MapServer"

but I need the index number of the layer appended to the end of the url. So how do I get a url of:

http://myserver:6080/ArcGIS/rest/services/MyLayers/MapServer/4

[VikramS · Accepted solution]

map.addLayer(DynamicmapService);

map.on("layers-add-result", function (evt) {

                layerInfo = dojo.map(evt.layers, function (layer, index) {
                                  var dynLayerInfos = map.getLayer(layer.layer.id).createDynamicLayerInfosFromLayerInfos();
                                 
                                   dynLayerInfos.forEach(function (layerInfo3) {
                                          var url = String (layer.layer.url) +"/" + layerInfo3.id;
            
                                     }
                 }

[ThomasRoussell]

Thanks so much vikram s.