如果我来自一个带有菜单的页面，菜单不会在页面上展开

Question

    function myFunction() {
      var x = document.getElementById("myTopnav");
      if (x.className === "topnav") {
        x.className += " responsive";
      } else {
        x.className = "topnav";
      }
    }
    
    $(document).ready(function($) {
      $('.links').click(function() {
        $("#myTopnav").removeClass("responsive");
      });
    });

   ul.topnav {
          list-style-type: none;
          margin: 0;
          padding: 0;
          overflow: hidden;
          background-color: #DDD;
        }
    
        ul.topnav li {float: left;}
    
        ul.topnav li a {
          display: inline-block;
          color: #B500FF;
          text-align: center;
          padding: 10px 10px;
          text-decoration: none;
          transition: 0.3s;
          font-size: 17px;
        }
    
        ul.topnav li a:hover {background-color: #555;color: #000;}
    
        ul.topnav li a:visited {color: #B500FF;}
    
        ul.topnav li.icon {display: none;}
    
          ul.topnav li:not(:first-child) {display: none;}
          ul.topnav li.icon {
            float: right;
            display: inline-block;
          }
          ul.topnav.responsive {position: relative;}
          ul.topnav.responsive li.icon {
            position: absolute;
            right: 0;
            top: 0;
          }
          ul.topnav.responsive li {
            float: none;
            display: inline;
          }
          ul.topnav.responsive li a {
            display: block;
            text-align: left;
          }
        @media screen and (max-width:680px) {
        }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div id="inner">
        <ul class="topnav" id="myTopnav">
          <li class="links"><a class="active" href="index.php">Home</a></li>
          <li class="links"><a href="bio.php">Bio</a></li>
          <li class="links"><a href="portfolio.php">Protfolio</a></li>
          <li class="links"><a href="film.php">&nbsp;&nbsp;- Film</a></li>
          <li class="links"><a href="clocks.php">&nbsp;&nbsp;- Clocks</a></li>
          <li class="links"><a href="machinery.php">&nbsp;&nbsp;- Machinery</a></li>
          <li class="links"><a href="truck.php">&nbsp;&nbsp;- Set Truck</a></li>
          <li class="links"><a href="for_sale.php">For Sale</a></li>
          <li class="links"><a href="for_sale.php?s=clocks">&nbsp;&nbsp;- Clocks</a></li>
          <li class="links"><a href="for_sale.php?s=memorabilia.php">&nbsp;&nbsp;- Movie Memorabilia</a></li>
          <li class="links"><a href="for_sale.php?s=stuff.php">&nbsp;&nbsp;- Stuff</a></li>
          <li class="links"><a href="stuff.php">Cool Stuff</a></li>
          <li class="links"><a href="contact.php">Contact Us</a></li>
          <li class="icon">
            <a href="javascript:void(0);" style="font-size:15px;" onclick="myFunction()">&#9776;</a>
          </li>
        </ul>
      </div>

我从堆栈中获取此代码，它工作正常，直到我使用链接到页面，其上有相同的菜单，然后它不会展开这个新页面上的菜单。 如果我重新加载页面菜单然后工作正常。