原生js tab 欄切換

<div id="box">
<div>
  <button>按鈕1</button>
  <button>按鈕2</button>
</div>
<div>
   <div>內容1</div>
   <div>內容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;//為每個按鈕添加一個特有的標記
 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指的是點擊對象
divs[this.index].style.display = "block";
}
}