原生JS实现拖拽图片效果

  #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;  }

<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>

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   */  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;    }  }