javascript获取隐藏dom的宽高 具体实现

首先clone一个DOM，设置position:absolute，然后设置top为一个比较大的负值，然后使其显示出来，最后获取到了DOM的宽高后，将其remove。
具体代码如下：
Js代码

function getCss(elem, css){  
 if (window.getComputedStyle) {  
  return window.getComputedStyle(elem, null)[css];  
 }else if (elem.currentStyle) {  
  return elem.currentStyle[css];  
 }else {  
  return elem.style[css];  
 }  
}  
function getWH(dom){  
 var get = function(elem){  
  var wh = {};  
  'Width Height'.replace(/[^ ]+/g, function(i){  
   var a = i.toLowerCase();  
   wh[a] = elem['offset' + i] || elem['client' + i];  
  });  
  return wh;  
 };  
 if (getCss(dom, 'display') === 'none') {  
  var nDom = dom.cloneNode(true);  
  nDom.style.position = 'absolute';  
  nDom.style.top = '-3000px';  
  nDom.style.display = 'block';  
  document.getElementsByTagName('body')[0].appendChild(nDom);  
  var wh = get(nDom);  
  nDom.parentNode.removeChild(nDom);  
  return wh;  
 }   
 return get(dom);  
}  
//test   
console.log(getWH(document.getElementById('content')));  
var domA = document.createElement("a"), _ostyle = "position:absolute;z-index:999999;width:92px;height:22px;position:absolute;display:none;";  
domA.setAttribute("style", _ostyle);  
domA.style.cssText = _ostyle;  
domA.setAttribute("href", "javascript:void(0);");  
document.getElementsByTagName('body')[0].appendChild(o);  
console.log(getWH(domA)); 
function getCss(elem, css){
 if (window.getComputedStyle) {
  return window.getComputedStyle(elem, null)[css];
 }else if (elem.currentStyle) {
  return elem.currentStyle[css];
 }else {
  return elem.style[css];
 }
}
function getWH(dom){
 var get = function(elem){
  var wh = {};
  'Width Height'.replace(/[^ ]+/g, function(i){
   var a = i.toLowerCase();
   wh[a] = elem['offset' + i] || elem['client' + i];
  });
  return wh;
 };
 if (getCss(dom, 'display') === 'none') {
  var nDom = dom.cloneNode(true);
  nDom.style.position = 'absolute';
  nDom.style.top = '-3000px';
  nDom.style.display = 'block';
  document.getElementsByTagName('body')[0].appendChild(nDom);
  var wh = get(nDom);
  nDom.parentNode.removeChild(nDom);
  return wh;
 }
 return get(dom);
}
//test
console.log(getWH(document.getElementById('content')));
var domA = document.createElement("a"), _ostyle = "position:absolute;z-index:999999;width:92px;height:22px;position:absolute;display:none;";
domA.setAttribute("style", _ostyle);
domA.style.cssText = _ostyle;
domA.setAttribute("href", "javascript:void(0);");
document.getElementsByTagName('body')[0].appendChild(o);
console.log(getWH(domA));

还有其他更好的方法欢迎提出来。