div拖曳

var x1, y1;
$(document).ready(function() {
    $(".headDiv").mousedown(
     function(event) {
         var offset = $("#move_div").offset();
         x1 = event.clientX - offset.left;
         y1 = event.clientY - offset.top;

         $(document).mousemove(function(event) {
             $(".moveDiv").css("left", (event.clientX - x1) + "px");
             $(".moveDiv").css("top", (event.clientY - y1) + "px");
         });
     })
    $(".headDiv").mouseup(
     function(event) {
         $(document).unbind("mousemove");
     });
});