【兼容性问题解决】封装getByClass,getElementsByClassName IE低不兼容解决
    <!doctype html>
 <html>
 <head>
 <meta charset="utf-8">
 <meta name="author" content="前端工程师——和派孔明" />
 <meta name="copyright" content="前端工程师——和派孔明" />
 <title>getElementsByClassName IE低不兼容解决</title>
 <style>
 * {
margin: 0;
padding: 0;
list-style: none;
font-family: "微软雅黑", "张海山锐线体简"
 }
 div {
height: 50px;
background: #ccc;
margin: 10px;
 }
 </style>
 <script>
 window.οnlοad=function(){
var aBox = getByClass(document,'box');
for(var i=0;i<aBox.length;i++){
aBox[i].style.background='red';
 
}
 };
function getByClass(oParent,sClass){
var aEle = oParent.getElementsByTagName('*');//父级获取下面所有
var result=[];//准备空数组
for(var i=0;i<aEle.length;i++){
//临时数组,装切出来的单个aEle 元素的class
var tmpArr = aEle[i].className.split(' ');//[box a b c d e f g]
for(var j=0;j<tmpArr.length;j++){
if(tmpArr[j] == sClass){//数组里每一个字符和传入的box对比
result.push(aEle[i]); 
break;
}
}
} 
return result;
 }
 </script>
 </head>
 <body>
     <div class="box a b c d e f g">box a b c d e f g</div>
     <div class="">空</div>
     <p class="active box">active box</p>
     <div>空</div>
     <div class="a_box_b">a_box_b</div>
 </body>
 </html>