js中getBoundingClientRect的作用及兼容方案详解

var box=document.getElementById('box'); // 获取元素

alert(box.getBoundingClientRect().top); // 元素上边距离页面上边的距离

alert(box.getBoundingClientRect().right); // 元素右边距离页面左边的距离

alert(box.getBoundingClientRect().bottom); // 元素下边距离页面上边的距离

alert(box.getBoundingClientRect().left); // 元素左边距离页面左边的距离

<div id="test" style="width: 100px; height: 100px; background: #ddd;"></div>
<script>
 function getObjXy(obj){
  var xy = obj.getBoundingClientRect();
  var top = xy.top-document.documentElement.clientTop+document.documentElement.scrollTop,//document.documentElement.clientTop 在IE67中始终为2，其他高级点的浏览器为0
   bottom = xy.bottom,
   left = xy.left-document.documentElement.clientLeft+document.documentElement.scrollLeft,//document.documentElement.clientLeft 在IE67中始终为2，其他高级点的浏览器为0
   right = xy.right,
   width = xy.width||right - left, //IE67不存在width 使用right - left获得
   height = xy.height||bottom - top;

  return {
   top:top,
   right:right,
   bottom:bottom,
   left:left,
   width:width,
   height:height
  }
 }

 var test = getObjXy(document.getElementById('test'));
 alert("top:" + test.top + ", right:" + test.right + ", bottom:" + test.bottom + ", left:" + test.left);
</script>