Question

我按照此link尝试制作可点击的下拉菜单。

我注意到链接中的代码是针对一个下拉菜单的，我认为此代码用于创建下拉菜单。

<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown</button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home</a>
<a href="#about">About</a>
<a href="#contact">Contact</a>
</div>
</div>

我尝试创建另外两个下拉菜单，因此我将上面的代码复制两次

2nd dropdown 
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown2</button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home2</a>
<a href="#about">About2</a>
<a href="#contact">Contact2</a>
</div>
</div>

3rd dropdown
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown3</button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home2</a>
<a href="#about">About2</a>
<a href="#contact">Contact2</a>

我没有编辑标签和标签内的任何内容，因此我点击链接上的运行以查看结果。

只有第一个下拉菜单（原始菜单）可以显示菜单，另外两个下拉菜单不显示任何内容。

我想原因是第二个下拉菜单和第三个下拉菜单在和标签内没有正确的内容。所以我开始修改代码和标记。

以下是我为第二个下拉列表和第三个下拉菜单添加的完整代码。

<!DOCTYPE html>
<html>
<head>
<style>

/*1st dropdown*/
.dropbtn {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn:hover, .dropbtn:focus {
background-color: #3e8e41;
}

.dropdown {
position: relative;
display: inline-block;
}

.dropdown-content {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
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;}


/*2nd dropdown*/
.dropbtn2 {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn2:hover, .dropbtn2:focus {
background-color: #3e8e41;
}

.dropdown2 {
position: relative;
display: inline-block;
}

.dropdown-content2 {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
overflow: auto;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}

.dropdown-content2 a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}

.dropdown2 a:hover {background-color: #f1f1f1}

.show2 {display:block;}

/*3rd dropdown*/
.dropbtn3 {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn3:hover, .dropbtn2:focus {
background-color: #3e8e41;
}

.dropdown3 {
position: relative;
display: inline-block;
}

.dropdown-content3 {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
overflow: auto;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}

.dropdown-content3 a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}

.dropdown3 a:hover {background-color: #f1f1f1}

.show3 {display:block;}

</style>
</head>
<body>

<h2>Clickable Dropdown</h2>
<p>Click on the button to open the dropdown menu.</p>

1st dropdown
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown</button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home</a>
<a href="#about">About</a>
<a href="#contact">Contact</a>
</div>
</div>

2nd dropdown
<div class="dropdown2">
<button onclick="myFunction2()" class="dropbtn2">Dropdown2</button>
<div id="myDropdown2" class="dropdown-content2">
<a href="#home">Home2</a>
<a href="#about">About2</a>
<a href="#contact">Contact2</a>
</div>
</div>

3rd dropdown
<div class="dropdown3">
<button onclick="myFunction3()" class="dropbtn3">Dropdown3</button>
<div id="myDropdown3" class="dropdown-content3">
<a href="#home">Home3</a>
<a href="#about">About3</a>
<a href="#contact">Contact3</a>
</div>
</div>

<script>
/* When the user clicks on the button, 
toggle between hiding and showing the dropdown content */
function myFunction() {
document.getElementById("myDropdown").classList.toggle("show");
}

// Close the dropdown 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');
  }
  }
  }
  }

//for 2nd dropdown
function myFunction2() {
document.getElementById("myDropdown2").classList.toggle("show2");
}

// Close the dropdown if the user clicks outside of it
window.onclick = function(event) {
if (!event.target.matches('.dropbtn2')) {

var dropdowns = document.getElementsByClassName("dropdown-content2");
var i;
for (i = 0; i < dropdowns.length; i++) {
  var openDropdown = dropdowns[i];
  if (openDropdown.classList.contains('show2')) {
    openDropdown.classList.remove('show2');
  }
}
}
}

//for 3rd dropdown

function myFunction3() {
document.getElementById("myDropdown3").classList.toggle("show3");
}

// Close the dropdown if the user clicks outside of it
window.onclick = function(event) {
if (!event.target.matches('.dropbtn3')) {

var dropdowns = document.getElementsByClassName("dropdown-content3");
var i;
for (i = 0; i < dropdowns.length; i++) {
  var openDropdown = dropdowns[i];
  if (openDropdown.classList.contains('show3')) {
    openDropdown.classList.remove('show3');
  }
}
}
}

</script>
</body>
</html>

当我运行代码时，所有按钮都可以在单击时打开下拉菜单。但是，当我在下拉菜单外单击时，只有第三个按钮可以关闭下拉菜单，第一个和第二个按钮仍然打开下拉菜单。

以下是我的问题。

复制另外两组代码创建另外两个下拉菜单似乎不是一个好习惯，因为代码会变得凌乱，不适合调试，即使有更新，我也多次更改代码。

但是，如果不复制另外两组代码，则另外两个下拉菜单将无效。

即使我复制了另外两组代码来创建另外两个下拉菜单，我也不明白当鼠标点击它们时，下拉菜单不会关闭。

请感谢您的建议。谢谢。

Answer 1

你要覆盖三次window.onclick事件功能。只有最后一个功能启动。如果将三个功能合二为一，则可以正常工作。

您现在的代码：

<!DOCTYPE html>
<html>
<head>
<style>

/*1st dropdown*/
.dropbtn {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn:hover, .dropbtn:focus {
background-color: #3e8e41;
}

.dropdown {
position: relative;
display: inline-block;
}

.dropdown-content {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
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;}


/*2nd dropdown*/
.dropbtn2 {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn2:hover, .dropbtn2:focus {
background-color: #3e8e41;
}

.dropdown2 {
position: relative;
display: inline-block;
}

.dropdown-content2 {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
overflow: auto;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}

.dropdown-content2 a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}

.dropdown2 a:hover {background-color: #f1f1f1}

.show2 {display:block;}

/*3rd dropdown*/
.dropbtn3 {
background-color: #4CAF50;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}

.dropbtn3:hover, .dropbtn2:focus {
background-color: #3e8e41;
}

.dropdown3 {
position: relative;
display: inline-block;
}

.dropdown-content3 {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
overflow: auto;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}

.dropdown-content3 a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}

.dropdown3 a:hover {background-color: #f1f1f1}

.show3 {display:block;}

</style>
</head>
<body>

<h2>Clickable Dropdown</h2>
<p>Click on the button to open the dropdown menu.</p>

1st dropdown
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn">Dropdown</button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home</a>
<a href="#about">About</a>
<a href="#contact">Contact</a>
</div>
</div>

2nd dropdown
<div class="dropdown2">
<button onclick="myFunction2()" class="dropbtn2">Dropdown2</button>
<div id="myDropdown2" class="dropdown-content2">
<a href="#home">Home2</a>
<a href="#about">About2</a>
<a href="#contact">Contact2</a>
</div>
</div>

3rd dropdown
<div class="dropdown3">
<button onclick="myFunction3()" class="dropbtn3">Dropdown3</button>
<div id="myDropdown3" class="dropdown-content3">
<a href="#home">Home3</a>
<a href="#about">About3</a>
<a href="#contact">Contact3</a>
</div>
</div>

<script>
/* When the user clicks on the button, 
toggle between hiding and showing the dropdown content */
function myFunction() {
    document.getElementById("myDropdown").classList.toggle("show");
}

//for 2nd dropdown
function myFunction2() {
    document.getElementById("myDropdown2").classList.toggle("show2");
}



//for 3rd dropdown

function myFunction3() {
    document.getElementById("myDropdown3").classList.toggle("show3");
}

// Close the dropdown 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');
        }
    }
  }
  
  if (!event.target.matches('.dropbtn2')) {

    var dropdowns = document.getElementsByClassName("dropdown-content2");
    var i;
    for (i = 0; i < dropdowns.length; i++) {
        var openDropdown = dropdowns[i];
        if (openDropdown.classList.contains('show2')) {
            openDropdown.classList.remove('show2');
        }
    }
  }
  
  if (!event.target.matches('.dropbtn3')) {

    var dropdowns = document.getElementsByClassName("dropdown-content3");
    var i;
    for (i = 0; i < dropdowns.length; i++) {
        var openDropdown = dropdowns[i];
        if (openDropdown.classList.contains('show3')) {
            openDropdown.classList.remove('show3');
        }
    }
  }
}




</script>
</body>
</html>

关于可点击的下拉菜单

1 个答案: