JS实现 div拖拽 限制在屏幕内 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style>
#div1 {width:100px; height:100px; background:red; position:absolute;}
div {width:3px; height:3px; position:absolute; background:black;}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
window.onload=function ()
{
    var oDiv=document.getElementById('div1');
    
    oDiv.onmousedown=function (ev)
    {
        var oEvent=ev||event;
        
        var disX=oEvent.clientX-oDiv.offsetLeft;
        var disY=oEvent.clientY-oDiv.offsetTop;
        
        document.onmousemove=function (ev)
        {
            var oEvent=ev||event;
            
            var l=oEvent.clientX-disX;
            var t=oEvent.clientY-disY;
            
            if(l <=0 ){
                oDiv.style.left = 0
            }else if(oEvent.clientX >= document.body.clientWidth){
                oDiv.style.left = oEvent.clientX - oDiv.offsetWidth + 'px'
            }else{
                oDiv.style.left=l+'px';
            }
            if(t <=0 ){
                oDiv.style.top = 0
            }else if(oEvent.clientY >= document.body.clientHeight){
                oDiv.style.top = oEvent.clientY - oDiv.offsetHeight + 'px'
            }else{
                oDiv.style.top=t+'px';
            }
        };
        
        document.onmouseup=function ()
        {
            document.onmousemove=null;
            document.onmouseup=null;
        };
    };
};

</script>
</head>

<body>
<div id="div1">
</div>
</body>
</html>

 

posted @ 2017-01-13 14:34  miaomiaotab  阅读(661)  评论(0)    收藏  举报