原生js实现图片图标拖拽

功能概要：

1. 原生JS实现图标图拖拽，拖拽的过程中不断输出该div的left、top值。

2. 用html5的drag来实现拖拽有兼容性问题，使用拖拽插件代码又很多，而这个拖拽demo代码少，并且兼容所有浏览器，很值得在项目中使用，

css样式：

   #div1{ 
       width: 100px; height: 100px; 
       background-color: #4D4D4D; 
       position: absolute; cursor: pointer; 
       -webkit-box-shadow: 3px 3px 0px 3px #C7C7C7; 
       box-shadow: 3px 3px 3px 0px #C7C7C7; 
   }
   #parent{ 
       width: 500px; height: 500px; 
       border: 1px solid #CDCDCD; 
       position: relative; margin: 0 auto;   //父级元素设置为：
       background-color: #F4F4F4; 
   }
   .postText{
       width: 500px; height: 30px;margin: 0 auto; background-color: #F4F4F4;
   }
   .postText span{ 
      padding:0px 10px;
   }

html代码

<div id="parent">
    <div id="div1" onmousemove="posMove(this.id)"></div>
</div>
<div class="postText">
   移动的距离Top：<span id="posTop"></span>Left:<span id="posLeft"></span>
</div>

js代码及注释:

    function posMove(getdivid) {
        var oDiv = document.getElementById(getdivid);
        var oParent = document.getElementById('parent');
        var sent = {
            l: 10,  //设置div在父元素的活动范围，10相当于给父div设置padding-left：10;
            r: oParent.offsetWidth - oDiv.offsetWidth,  // offsetWidth:当前对象的宽度， offsetWidth = width+padding+border
            t: 10,
            b: oParent.offsetHeight - oDiv.offsetHeight,
            n: 10
        }
        drag(oDiv, sent);  
    }
    
   /**
     *
     * @param obj:被拖动的div
     * @param sent :设置div在容器中可以被拖动的区域
     * 原作者的插件下载地址如下: http://www.jq22.com/jquery-info4543
     */
    function drag(obj,sent){

        var dmW = document.documentElement.clientWidth || document.body.clientWidth;
        var dmH = document.documentElement.clientHeight || document.body.clientHeight;

        var sent = sent || {};
        var l = sent.l || 0;
        var r = sent.r || dmW - obj.offsetWidth;
        var t = sent.t || 0;
        var b = sent.b || dmH - obj.offsetHeight;
        var n = sent.n || 10;

        obj.onmousedown = function (ev){
            var oEvent = ev || event;
            var sentX = oEvent.clientX - obj.offsetLeft;
            var sentY = oEvent.clientY - obj.offsetTop;

            document.onmousemove = function (ev){
                var oEvent = ev || event;

                var slideLeft = oEvent.clientX - sentX;
                var slideTop = oEvent.clientY - sentY;

                if(slideLeft <= l){
                    slideLeft = l;
                }
                if(slideLeft >= r){
                    slideLeft = r;
                }
                if(slideTop <= t){
                    slideTop = t;
                }
                if(slideTop >= b){
                    slideTop = b;
                }

                obj.style.left = slideLeft + 'px';
                obj.style.top = slideTop + 'px';

                document.getElementById('posTop').innerHTML = slideTop;
                document.getElementById('posLeft').innerHTML = slideLeft;

            };
            document.onmouseup = function (){
                document.onmousemove = null;
                document.onmouseup = null;
            }

            return false;
        }
    }

event对象的clientX,offsetX,screenX,pageX的区别：

ps： 若有错误，请指出，谢谢，大家共同学习进步~~~