比较精简的Javascript拖动效果函数代码

http://www.jb51.net/article/10578.htm

<html>  
<head><title>拖动效果函数演示 by Longbill.cn</title>  
<style>  
body   
{  
    font-size:12px;  
    color:#333333;  
    border : 0px solid blue;  
}  
div  
{  
    position : absolute;  
    background-color : #c3d9ff;  
    margin : 0px;  
    padding : 5px;  
    border : 0px;  
    width : 100px;  
    height:100px;  
}  
</style>  
</head>  
<body>  
<script>  
function drag(o,s)  
{  
    if (typeof o == "string") o = document.getElementById(o);  
    o.orig_x = parseInt(o.style.left) - document.body.scrollLeft;  
    o.orig_y = parseInt(o.style.top) - document.body.scrollTop;  
    o.orig_index = o.style.zIndex;  
          
    o.onmousedown = function(a)  
    {  
        this.style.cursor = "move";  
        this.style.zIndex = 10000;  
        var d=document;  
        if(!a)a=window.event;  
        var x = a.clientX+d.body.scrollLeft-o.offsetLeft;  
        var y = a.clientY+d.body.scrollTop-o.offsetTop;  
        //author: www.longbill.cn  
        d.ondragstart = "return false;"  
        d.onselectstart = "return false;"  
        d.onselect = "document.selection.empty();"  
                  
        if(o.setCapture)  
            o.setCapture();  
        else if(window.captureEvents)  
            window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);  

        d.onmousemove = function(a)  
        {  
            if(!a)a=window.event;  
            o.style.left = a.clientX+document.body.scrollLeft-x;  
            o.style.top = a.clientY+document.body.scrollTop-y;  
            o.orig_x = parseInt(o.style.left) - document.body.scrollLeft;  
            o.orig_y = parseInt(o.style.top) - document.body.scrollTop;  
        }  

        d.onmouseup = function()  
        {  
            if(o.releaseCapture)  
                o.releaseCapture();  
            else if(window.captureEvents)  
                window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);  
            d.onmousemove = null;  
            d.onmouseup = null;  
            d.ondragstart = null;  
            d.onselectstart = null;  
            d.onselect = null;  
            o.style.cursor = "normal";  
            o.style.zIndex = o.orig_index;  
        }  
    }  
      
    if (s)  
    {  
        var orig_scroll = window.onscroll?window.onscroll:function (){};  
        window.onscroll = function ()  
        {  
            orig_scroll();  
            o.style.left = o.orig_x + document.body.scrollLeft;  
            o.style.top = o.orig_y + document.body.scrollTop;  
        }  
    }  
}  
</script>  

<div id="div1" style="left:10px;top:10px;">div1:我可以被拖动</div>  
<div id="div2" style="left:120px;top:10px;background-color : #f3d9ff">div2:来拖我呀</div>  
<div id="div3" style="left:230px;top:10px;background-color : #c3ffff">div3:我随便你拖</div>  
<div id="div4" style="left:10px;top:120px;background-color : #c3d944">div4:我可以随窗口滑动，把我拖到最下面，然后滚动网页看看</div>  
<div id="div5" style="left:120px;top:120px;background-color : #f3d944">作者: Longbill
<a href=http://www.longbill.cn target=_blank>www.longbill.cn</a>  
</div>  
<div id="div6" style="left:230px;top:120px;background-color : #e3f944;200px;">参数说明:
  
drag(obj [,scroll]);
  
obj:对象的id或对象本身;
  
scroll(可选):对象是否随窗口拖动而滑动，默认为否
  
鼠标右键查看源代码  
</div>  


<script>  
drag("div1");  
drag("div2");  
drag("div3");  
drag("div4",1);  
drag("div5",1);  
drag("div6",1);  


</script>  

</body>

avascript 简单实现鼠标拖动DIV

博客分类：

Javascript

javascript 拖动DIV

Javascript简单的实现鼠标拖动DIV的效果。没有什么技术含量，全当笔记。
要想实现鼠标拖动效果，免不了要计算元素在浏览器中的坐标，那首先来学习一下各种坐标。
参考：
Javascript获取页面的各种坐标汇总

实现拖动：
1.定义需要的变量

Javascript代码

var bool=false,
pageX=0,
pageY=0,
//需要拖动的目标DIV
element = $("#tb_window"),
eWidth = element.width(),
eHeight = element.height(),
//在该DIV的范围内拖动
pElement = $("#flashFrame"),
pWidth = pElement.width(),
pHeight = pElement.height();

2.鼠标mousedown事件计算鼠标焦点x相对目标DIV的坐标

Javascript代码

element.mousedown(function(event)
{
needMove=true;
var position = element.position();
pageX = event.pageX-position.left; //鼠标和DIV的相对坐标
pageY = event.pageY-position.top;
element.css('cursor','move');
});

3.鼠标mouseup事件将变量needMove赋值false，表示不需要移动DIV

Javascript代码

element.mouseup(function(event)
{
needMove=false;
});

4.鼠标的mousemove事件开始移动目标DIV

Javascript代码

element.mousemove(function(event)
{
if(!needMove) {return;}
//鼠标在页面的坐标 - 鼠标和DIV的相对坐标 = DIV在页面的坐标
var ePageX = event.pageX;
var ePageY = event.pageY;
var x = ePageX-pageX;
var y = ePageY-pageY;
if (ePageX <= eWidth/ 2 || ePageX >= pWidth - eWidth / 2)
{
return;
}
if (ePageY< eHeight / 2 || ePageY >= pHeight - eHeight / 2)
{
return;
}
element.css("left", x);
element.css("top", y);
});

5.总结，以上代码只是简单实现鼠标拖动DIV的思路（当然功能也是可以的），具体的性能，兼容性和代码扩展性都有待商榷。比如：还可以增加参数控制DIV在指定的大小范围内拖动等。