Yes.var centerPt=null; //description:get distance between ptB and centerPt //return: number function getDistance(ptB){ if(centerPt==null||centerPt.mapPoint==null){ console.log("unexpected para,function getDistance()"); return ""; } var ptA=centerPt.mapPoint; return Math.sqrt(Math.pow(ptA.x-ptB.x,2)+Math.pow(ptA.y-ptB.y,2)); } //onDragStart, record the centerPt dojo.connect(mapAppObj.map,"onMouseDragStart",function(evt){ console.log("dragStart triggered"); centerPt=evt; }); } //onDrag, calculate distance between currentPoint and centerPt dojo.connect(mapAppObj.map,"onMouseDrag",function(evt){ var radius=getDistance(evt.mapPoint); console.log("radius is:"+radius); }