我正在使用 html 和 css 为一个大学元素创建一个网站，我正在尝试添加一个下拉菜单。我遵循了 w3Schools 的教程，但出于某种原因，当我单击按钮打开菜单时，它不会保持打开状态并立即消失。我已经尽可能多地查看了我的代码，但看不出它有什么问题。谢谢
这是我的 CSS 代码:
body{
background-color: black;
}
header, footer{
color: black;
background-color: red;
padding: 1em;
text-align: center;
}
.dropbtn{
background-color: #FF0000;
color: black;
padding: 8px;
font-size: 12px;
border: none;
cursor: pointer;
}
.confirmbtn {
margin: 10px 0;
}
.dropbtn:hover, .dropbtn:focus {
background-color: #B20000;
}
.dropdown{
position: relative;
display: inline-block;
}
.dropdown-content {
display: none;
position: absolute;
background-color: #F6F6F6;
min-width: 50px;
overflow: auto;
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 a:hover { background-color: #f1f1f1; }
.show { display: block; }
article{
margin-left: 200px;
border-left: 2px solid red;
border-right: 2px solid red;
padding: 1em;
height: 600px;
background-color: black;
color: red;
z-index: 1;
}
form{
text-align: center;
}
textarea{
display: block;
margin-left: auto;
margin-right: auto;
}
li{
margin: 10px 0;
}
image{
height: 100px;
}
nav{
float: left;
border-left: 2px solid red;
max-width: 190px;
padding: 1em;
height: 600px;
background-color: black;
}
这是我正在处理的页面的 html 代码:
<DOCTYPE! html>
<html>
<head>
<title> Purchase Games </title>
<link rel="stylesheet" href="style.css">
<script>
function submitData(){
var firstname = document.forms["myForm"]["firstname"].value;
var lastname = document.forms["myForm"]["lastname"].value;
if(firstname == ""){
alert("Please enter something as your first name.");
return;
}
if(lastname == ""){
alert("Please enter something as your last name. ");
return;
}
}
function myFunction() {
document.getElementById("myDropdown").classList.toggle("show");
}
window.onclick = function(event) {
if(!event.target.matches('.dropbtn')){
var dropdowns = document.getElementsByClassName("dropdown-content");
for(var i = 0; i < dropdowns.length; i++){
var openDropdown = dropdowns[i];
if(openDropdown.classList.contains('show')){
openDropdown.classList.remove('show');
}
}
}
}
</script>
</head>
<body>
<div>
<header><h1> Games Collection </h1></header>
<nav>
<ul>
<li><a href="index.htm"> Home </a></li>
<li><a href="casual.htm"> Casual </a></li>
<li><a href="shooter.htm"> Shooter </a></li>
<li><a href="platformer.htm"> Platformer </a></li>
<li><a href="purchase.htm"> Purchase Games </a></li>
</ul>
</nav>
<article>
<h1> Purchase Games </h1>
<form name="myForm">
First Name: <br>
<input type="text" name="firstname"> <br> <br>
Last Name <br>
<input type="text" name="lastname"> <br> <br>
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn"> Select Game Code </button>
<div id="myDropdown" class="dropdown-content">
<a href="#"> FIFA </a>
<a href="#"> FORZA </a>
<a href="#"> POOL </a>
<a href="#"> MINE </a>
<a href="#"> PES </a>
<a href="#"> CODMW </a>
<a href="#"> TITAN </a>
<a href="#"> TITAN2 </a>
<a href="#"> BATTLE </a>
<a href="#"> PLANT </a>
<a href="#"> INSIDE </a>
<a href="#"> TERRA </a>
<a href="#"> MANY </a>
<a href="#"> MARIO </a>
<a href="#"> RYMAN </a>
</div>
</div>
<br>
<input type="submit" value="Confirm" class="confirmbtn" onclick="submitData()">
<br> <br>
</form>
<textarea rows="10" cols="50" id="myTextArea">
Once you purchase an item this is where it will appear
</textarea>
</article>
<footer><h3> Created by Michael Shepherd (Use this link: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_js_dropdown_filter" </h3></footer>
</div>
</body>
</html>
最佳答案
按钮的默认行为是提交。所以需要专门添加
<button type="button">Button</button>
所以在你的按钮上添加
<button type="button" onclick="myFunction()" class="dropbtn"> Select Game Code </button>
下面是最终代码
HTML
<div>
<header>
<h1> Games Collection </h1></header>
<nav>
<ul>
<li><a href="index.htm"> Home </a></li>
<li><a href="casual.htm"> Casual </a></li>
<li><a href="shooter.htm"> Shooter </a></li>
<li><a href="platformer.htm"> Platformer </a></li>
<li><a href="purchase.htm"> Purchase Games </a></li>
</ul>
</nav>
<article>
<h1> Purchase Games </h1>
<form name="myForm">
First Name:
<br>
<input type="text" name="firstname">
<br>
<br> Last Name
<br>
<input type="text" name="lastname">
<br>
<br>
<div class="dropdown">
<button type="button" onclick="myFunction()" class="dropbtn"> Select Game Code </button>
<div id="myDropdown" class="dropdown-content">
<a href="#"> FIFA </a>
<a href="#"> FORZA </a>
<a href="#"> POOL </a>
<a href="#"> MINE </a>
<a href="#"> PES </a>
<a href="#"> CODMW </a>
<a href="#"> TITAN </a>
<a href="#"> TITAN2 </a>
<a href="#"> BATTLE </a>
<a href="#"> PLANT </a>
<a href="#"> INSIDE </a>
<a href="#"> TERRA </a>
<a href="#"> MANY </a>
<a href="#"> MARIO </a>
<a href="#"> RYMAN </a>
</div>
</div>
<br>
<button type="submit" value="Confirm" class="confirmbtn" onclick="submitData()"></button>
<br>
<br>
</form>
<textarea rows="10" cols="50" id="myTextArea">
Once you purchase an item this is where it will appear
</textarea>
</article>
<footer>
<h3> Created by Michael Shepherd (Use this link: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_js_dropdown_filter" </h3></footer>
以及指向 JSfiddle 的链接
请记住将函数 myFunction() 放在 html 之前。我看到你在想什么。
关于javascript - 单击时 HTML 下拉菜单不会保持打开状态，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42853818/