<style>html,body{margin:0;padding:0;}.d1{margin-left:40px;background:red;width:2000px;height:100px;position:relative;}.d2{margin-left:40px;background:blue;width:1000px;height:80px;}</style><div id="d1" class="d1">    <div id="d2" class="d2"></div></div>

 1 function getWindow( elem ) { 2     return mylibs.isWindow( elem ) ? 3         elem : 4         elem.nodeType === 9 ? 5             elem.defaultView || elem.parentWindow : 6             false; 7 }; 8  9 var mylibs = {10     isWindow: function( obj ) {11         return obj != null && obj == obj.window;12     },13     //获取元素在浏览器中的绝对位置14     offset:function(elem){15         var docElem, win, clientTop, clientLeft, scrollTop, scrollLeft,16             box = { top: 0, left: 0 },17             doc = elem && elem.ownerDocument;18         19         docElem = doc.documentElement;20         //黑莓5 ios3(iphoe) 没有getBoundingClientRect21         if ( typeof elem.getBoundingClientRect !== "undefined" ) {22             box = elem.getBoundingClientRect();23         }24         win = getWindow( doc );25         26         clientTop  = docElem.clientTop  || document.body.clientTop  || 0;27         clientLeft = docElem.clientLeft || document.body.clientLeft || 0;28         scrollTop  = win.pageYOffset || docElem.scrollTop;29         scrollLeft = win.pageXOffset || docElem.scrollLeft;30         return {31             top: box.top  + scrollTop  - clientTop,32             left: box.left + scrollLeft - clientLeft33         };34     }35 };36 37 document.getElementById(‘d2‘).onclick = function(){38     alert(mylibs.offset(this).left);39 };