1-1

  1. <p>02</p>
  2. <a href="html/03.html">03.html</a>
  1.  <p>03</p>
  2.     <button id="btn">btn</button>
  3.   <script>
  4.      var btn =document.getElementById("btn");
  5.       btn.onclick=function(){
  6.             history.back();// 回到历史记录的上一步
  7.         }