<script>
dojo.require("esri.map");
var map;
function init() {
map = new esri.Map("map",{
basemap:"topo",
center:[-122.45,37.75], //long, lat
zoom:13,
sliderStyle:"small"
});
}
function getCenter(){
var centerLocation = map.extent.getCenter();
console.log(centerLocation.getLatitude());
console.log(centerLocation.getLongitude());
}
dojo.ready(init);
</script>
esri.geometry.webMercatorToGeographic(map.extent.getCenter());