练习

<ul>
  <li>html <button>删除</button></li>
    <li>css <button>删除</button></li>
      <li>js  <button>删除</button></li>
        </ul>            
var btns = document.getElementsByTagName("button")
        for(var i=0;i<btns.length;i++){
            btns[i].onclick = function(){
                var temp = window.confirm("确定吗")
                if(temp){
                    this.parentNode.style.display = "none"
                }
            }
        }