JavaScript拖拽事件

div拖拽案例：

html

     .kong{
             200px;
            height: 100px;
            background-color: yellowgreen;
            font-size: 32px;
            text-align: center;
            position: relative;
            top: 92px;
            left: 92px;
      }


      <div class="kong" id="test"></div>

JavaScript

<script>
    //拖拽事件
    var ele = document.getElementById("test");
    ele.onmousedown = function (ev) {
        var x1,y1,x2,y2,x,y,l,t,l2,t2;
        var ev = ev || event;
        l  = ele.offsetLeft;
        t  = ele.offsetTop;
        x1 = ev.clientX;
        y1 = ev.clientY;
        document.onmousemove = function (ev) {
            var ev = ev || event;
            x2 = ev.clientX;
            y2 = ev.clientY;
            x = x2-x1;
            y = y2-y1;
            l2 = x + l;
            t2 = y+ t;
            ele.style.left = l2+'px';
            ele.style.top  = t2+'px';
        };
        document.onmouseup = function(ev){
            document.onmousemove = null;
        };
    };
</script>

效果图: