js获取隐藏元素宽高的实现方法_javascript技巧

function getSize(id){
   var width,
     height,
     elem = document.getElementById(id),
     noneNodes = [],
     nodeStyle = [];
   getNoneNode(elem); //获取多层display：none;的元素
   setNodeStyle();
   width = elem.clientWidth;
   height = elem.clientHeight;
   resumeNodeStyle();
  
   return {
     width : width,
     height : height
   }

   function getNoneNode(node){
     var display = getStyles(node).getPropertyValue('display'),
        tagName = node.nodeName.toLowerCase();
     if(display != 'none'
        && tagName != 'body'){
        getNoneNode(node.parentNode);
     } else {
        noneNodes.push(node);
        if(tagName != 'body')
          getNoneNode(node.parentNode);
     }
   }
  
   //这方法才能获取最终是否有display属性设置，不能style.display。
   function getStyles(elem) {

     // Support: IE<=11+, Firefox<=30+ (#15098, #14150)
     // IE throws on elements created in popups
     // FF meanwhile throws on frame elements through "defaultView.getComputedStyle"
     var view = elem.ownerDocument.defaultView;

     if (!view || !view.opener) {
        view = window;
     }
     return view.getComputedStyle(elem);
   };
  
  
   function setNodeStyle(){
     var i = 0;
     for(; i < noneNodes.length; i++){
        var visibility = noneNodes[i].style.visibility,
        display = noneNodes[i].style.display,
        style = noneNodes[i].getAttribute("style");
        //覆盖其他display样式
        noneNodes[i].setAttribute("style", "visibility:hidden;display:block !important;" + style);
        nodeStyle[i] = {
          visibility :visibility,
          display : display
        }
     }       
   }
  
   function resumeNodeStyle(){
     var i = 0;
     for(; i < noneNodes.length; i++){
        noneNodes[i].style.visibility = nodeStyle[i].visibility;
        noneNodes[i].style.display = nodeStyle[i].display;
     }  

   }
}

var testSize = getSize('test');
console.log("test-> width:" + testSize.width + " height:" + testSize.height);

var test2ChildSize2 = getSize('test2_child');
console.log("test2Child2-> width:" + test2ChildSize2.width + " height:" + test2ChildSize2.height);

var test3ChildSize = getSize('test3_child');
console.log("test3_child-> width:" + test3ChildSize.width + " height:" + test3ChildSize.height);   
 
//打印值如下
test-> width:417 height:18
test2Child2-> width:417 height:18
test3_child-> width:417 height:18