原生js tab 栏切换

 <div id="box">
 <div>
   <button>按钮1</button>
   <button>按钮2</button>
 </div>
 <div>
    <div>内容1</div>
    <div>内容1</div>
 <div>
 <div>

 var btns = docuemnt.getElemetsByTagName("button");
 var divs = document.getElementsByClassName("con");

 for(var i =0; i < btns.length; i ++){
   btn[i].index = i;//为每个按钮添加一个特有的标记
  bth[i].onclick = functoin (){
 //排他思想
  for(var i =0; i<btn.length; i ++){

   btn[i].className = " ";
   divs[i].style.display = "none";
 }
  this.calssName = "current";//this指的是点击对象
 divs[this.index].style.display = "block";
 }
 }