Some Essential ArcGIS JS API commands for Quick retrieval of Map Properties

To get the current extent of a map:

JSON.stringify(map.extent.toJson())

 To get the current extent in geographic coordinates:

map.geographicExtent;

To get the center

map.geographicExtent.getCenter();

To get the current scale:

map.getScale();

To get the current zoom level:

map.getZoom();

Get more extent commands here: ArcGIS JSAPI Developer's Reference on extent-amd