getBoundingClientRect使用方法及兼容性处理

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

<p id="test" style="width: 100px; height: 100px; background: #ddd;"></p>
<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>