Why does my dropdown button throw me this error?-CodePudding

I'm getting a

Uncaught Reference Error : DropDown not defined

when I try to activate my dropdown. It is contained within a nav list but the error started even before that when it was contained within its own div in the header.

function  DropDown() {
  document.getElementById("myDropdown").classList.toggle("show");
}

// Close the dropdown menu if the user clicks outside of it
window.onclick  =   function(event) {  
  if  (!event.target.matches('.dropbtn'))  {    
    var  dropdowns = document.getElementsByClassName("dropdown-content");    
    var  i;    
    for  (i =  0; i < dropdowns.length; i  ) {      
      var  openDropdown = dropdowns[i];      
      if  (openDropdown.classList.contains('show'))  {       
        openDropdown.classList.remove('show');     
      }    
    } 
  }
}

body {
  margin: 0px;
}

#logo {
  width: 130px;
  float: left;
  padding-top: 13px;
  padding-bottom: 13px;
}

.container {
  width: 80%;
  margin: 0;
  float: left;
  padding: 0;
}

header {
  background-color: #55d6aa;
  padding: 0;
  margin: 0;
}

header::after {
  content: '';
  display: table;
  clear: both;
}

nav {
  float: right;
  font-size: 14px;
  margin: 0;
}

nav ul {
  margin: 0;
  padding: 0;
  list-style-type: none;
}

nav li {
  display: inline-block;
  margin: 0;
  padding-top: 23px;
  margin-left: 10px;
  position: relative;
}

nav a {
  color: black;
  text-decoration: none;
  text-transform: uppercase;
}

nav a:hover {
  color: darkblue;
}

nav a::before {
  content: '';
  display: block;
  height: 5px;
  width: 100%;
  background-color: black;
  top: 0;
  width: 0%;
  position: absolute;
  transition: all ease-in-out 250ms;
  border-radius: 10px 10px 10px 10px;
}

nav a:hover::before {
  width: 100%;
}

nav a:focus {
  background-color: #55d6aa;
}

#banner {
  width: 100%;
  height: 114px;
  margin: 0;
  padding: 0;
}

#barline {
  height: 30px;
  width: 100%;
  background-color: #55d6aa;
  margin: 0;
  padding: 0;
  float: right;
}

.dropbtn {
  background-color: #55d6aa;
  margin: 0;
  border: 0;
  color: black;
  text-decoration: none;
  text-transform: uppercase;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 60px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.show {
  display: block;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <title>Page title</title>
  <link rel="stylesheet" href="CSS/Style.css">
  <script type="javascript" src="Java/Java.js"></script>
</head>

<header>




  <div class="container">

    <img id="logo" src="IMG/Logo.png" alt="logo"></img>


    <nav>

      <ul>

        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Team</a></li>
        <li><a href="#">Contact</a></li>
        <li><a onclick="DropDown" class="dropbtn">MORE</a>
          <div id="myDropdown" class="dropdown-content">
            <a href="">Profile</a>
            <a href="">Settings</a>
            <a href="">Log Out</a>

          </div>
          </a>
        </li>

      </ul>

    </nav>

  </div>

</header>

<body>

  <div>

    <img id="banner" src="IMG/MountainBanner.jpg" alt="Mountains"></img>


  </div>

  <div id="barline">

  </div>





</body>

</html>

CodePudding user response：

when you click on drop-down button then DropDown Function works but you not define function---- soln:

<li><a onclick={DropDown} class="dropbtn">MORE</a>
                <div id="myDropdown" class="dropdown-content">

CodePudding user response：

You should move your <script/> tag to bottom of html code and move your header tag into body tag

<!DOCTYPE html>
<html lang="en">

<head>
  <title>Page title</title>
  <link rel="stylesheet" href="CSS/Style.css">
  
</head>
<body>
  <header>
   . . .
  </header>
  <div>
    <img id="banner" src="IMG/MountainBanner.jpg" alt="Mountains"></img>
  </div>

  <script type="javascript" src="Java/Java.js"></script>
</body>
</html>