鼠标点住移动div

如果拖动的是图片：事件中加入：e.preventDefault();

<div id='dv'></div>

<script type="text/javascript">
//获取元素
var dv = document.getElementById('dv');
var x = 0;
var y = 0;
var l = 0;
var t = 0;
var isDown = false;
//鼠标按下事件
dv.onmousedown = function(e)
{
    //获取x坐标和y坐标
    x = e.clientX;
    y = e.clientY;

    //获取左部和顶部的偏移量
    l = dv.offsetLeft;
    t = dv.offsetTop;
    //开关打开
    isDown = true;
    //设置样式    
    dv.style.cursor = 'move';

    //console.log(t);
}
//鼠标移动
window.onmousemove = function(e)
{
    if(isDown == false){
        return;
    }
    //获取x和y
    var nx = e.clientX;
    var ny = e.clientY;
    //计算移动后的左偏移量和顶部的偏移量
    var nl = nx-(x-l);
    var nt = ny-(y-t);

    dv.style.left = nl+'px';
    dv.style.top = nt+'px';

    //console.log();

}
//鼠标抬起事件
dv.onmouseup= function()
{
    //开关关闭
    isDown = false;
    dv.style.cursor = 'default';
}

</script>