我如何保持下拉菜单处于活动状态

时间：2018-07-03 07:38:17

标签： javascript html css

我想创建一个与此类似的下拉代码，但是进入页面时已经下拉了“下拉列表”，因此我不必喜欢单击或悬停它， 像已经打开的手风琴一样好，希望有人能提供帮助！我不知道该怎么解释。

我所知道的是，我希望它像我正在尝试编写的代码那样。 因此，我希望下拉菜单元素已经处于活动状态并可以显示，而不必单击或悬停。

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<style>
body {
    font-family: "Lato", sans-serif;
}

/* Fixed sidenav, full height */
.sidenav {
    height: 100%;
    width: 200px;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: #111;
    overflow-x: hidden;
    padding-top: 20px;
}

/* Style the sidenav links and the dropdown button */
.sidenav a, .dropdown-btn {
    padding: 6px 8px 6px 16px;
    text-decoration: none;
    font-size: 20px;
    color: #818181;
    display: block;
    border: none;
    background: none;
    width: 100%;
    text-align: left;
    cursor: pointer;
    outline: none;
}

/* On mouse-over */
.sidenav a:hover, .dropdown-btn:hover {
    color: #f1f1f1;
}

/* Main content */
.main {
    margin-left: 200px; /* Same as the width of the sidenav */
    font-size: 20px; /* Increased text to enable scrolling */
    padding: 0px 10px;
}

/* Add an active class to the active dropdown button */
.active {
    background-color: green;
    color: white;
}

/* Dropdown container (hidden by default). Optional: add a lighter background color and some left padding to change the design of the dropdown content */
.dropdown-container {
    display: none;
    background-color: #262626;
    padding-left: 8px;
}

/* Optional: Style the caret down icon */
.fa-caret-down {
    float: right;
    padding-right: 8px;
}

/* Some media queries for responsiveness */
@media screen and (max-height: 450px) {
    .sidenav {padding-top: 15px;}
    .sidenav a {font-size: 18px;}
}
</style>
</head>
<body>

<div class="sidenav">
  <a href="#about">About</a>
  <a href="#services">Services</a>
  <a href="#clients">Clients</a>
  <a href="#contact">Contact</a>
  <button class="dropdown-btn">Dropdown 
    <i class="fa fa-caret-down"></i>
  </button>
  <div class="dropdown-container">
    <a href="#">Link 1</a>
    <a href="#">Link 2</a>
    <a href="#">Link 3</a>
  </div>
  <a href="#contact">Search</a>
</div>

<div class="main">
  <h2>Sidebar Dropdown</h2>
  <p>Click on the dropdown button to open the dropdown menu inside the side navigation.</p>
  <p>This sidebar is of full height (100%) and always shown.</p>
  <p>Some random text..</p>
</div>

<script>
/* Loop through all dropdown buttons to toggle between hiding and showing its dropdown content - This allows the user to have multiple dropdowns without any conflict */
var dropdown = document.getElementsByClassName("dropdown-btn");
var i;

for (i = 0; i < dropdown.length; i++) {
  dropdown[i].addEventListener("click", function() {
    this.classList.toggle("active");
    var dropdownContent = this.nextElementSibling;
    if (dropdownContent.style.display === "block") {
      dropdownContent.style.display = "none";
    } else {
      dropdownContent.style.display = "block";
    }
  });
}
</script>

</body>
</html>

2 个答案:

答案 0 :(得分：0)

.dropdown-container {
    display: block;
    background-color: #262626;
    padding-left: 8px;
}

将display: none;替换为display: block;

这是结果

/* Loop through all dropdown buttons to toggle between hiding and showing its dropdown content - This allows the user to have multiple dropdowns without any conflict */
var dropdown = document.getElementsByClassName("dropdown-btn");
var i;

for (i = 0; i < dropdown.length; i++) {
  dropdown[i].addEventListener("click", function() {
    this.classList.toggle("active");
    var dropdownContent = this.nextElementSibling;
    if (dropdownContent.style.display === "block") {
      dropdownContent.style.display = "none";
    } else {
      dropdownContent.style.display = "block";
    }
  });
}
body {
    font-family: "Lato", sans-serif;
}

/* Fixed sidenav, full height */
.sidenav {
    height: 100%;
    width: 200px;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: #111;
    overflow-x: hidden;
    padding-top: 20px;
}

/* Style the sidenav links and the dropdown button */
.sidenav a, .dropdown-btn {
    padding: 6px 8px 6px 16px;
    text-decoration: none;
    font-size: 20px;
    color: #818181;
    display: block;
    border: none;
    background: none;
    width: 100%;
    text-align: left;
    cursor: pointer;
    outline: none;
}

/* On mouse-over */
.sidenav a:hover, .dropdown-btn:hover {
    color: #f1f1f1;
}

/* Main content */
.main {
    margin-left: 200px; /* Same as the width of the sidenav */
    font-size: 20px; /* Increased text to enable scrolling */
    padding: 0px 10px;
}

/* Add an active class to the active dropdown button */
.active {
    background-color: green;
    color: white;
}

/* Dropdown container (hidden by default). Optional: add a lighter background color and some left padding to change the design of the dropdown content */
.dropdown-container {
    display: block;
    background-color: #262626;
    padding-left: 8px;
}

/* Optional: Style the caret down icon */
.fa-caret-down {
    float: right;
    padding-right: 8px;
}

/* Some media queries for responsiveness */
@media screen and (max-height: 450px) {
    .sidenav {padding-top: 15px;}
    .sidenav a {font-size: 18px;}
}
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

<div class="sidenav">
  <a href="#about">About</a>
  <a href="#services">Services</a>
  <a href="#clients">Clients</a>
  <a href="#contact">Contact</a>
  <button class="dropdown-btn">Dropdown 
    <i class="fa fa-caret-down"></i>
  </button>
  <div class="dropdown-container">
    <a href="#">Link 1</a>
    <a href="#">Link 2</a>
    <a href="#">Link 3</a>
  </div>
  <a href="#contact">Search</a>
</div>

<div class="main">
  <h2>Sidebar Dropdown</h2>
  <p>Click on the dropdown button to open the dropdown menu inside the side navigation.</p>
  <p>This sidebar is of full height (100%) and always shown.</p>
  <p>Some random text..</p>
</div>

答案 1 :(得分：0)

尝试一下

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.dropbtn {
    background-color: #3498DB;
    color: white;
    padding: 16px;
    font-size: 16px;
    border: none;
    cursor: pointer;
}

.dropbtn:hover, .dropbtn:focus {
    background-color: #2980B9;
}

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

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f1f1f1;
    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: #ddd;}

.show {display: block;}
</style>
</head>
<body>

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

<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">Profile</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');
      }
    }
  }
}
</script>

</body>
</html>

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