This is a property you can configure when you create your map object. It's an option (the second, optional parameter for a map object). From the documentation:<Boolean> wrapAround180 When true, supports continuous pan across the dateline. Wraparound is supported in the following cases: Map spatial reference is WGS84 or Web Mercator The tiling scheme is either the pre-9.3 ArcGIS Online (4326) tiling scheme or ArcGIS/Google Maps/ Bing tiling scheme. Dynamic services must be version 10 or greater.At version 3.1 the default value is true. For versions earlier than 3.1 the default value is false.http://developers.arcgis.com/en/javascript/jsapi/map.html#map1