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首页 > 解决方案 > 如何在下拉容器中使用过渡，使其缓慢显示，直到达到我想要的大小？

javascript - 如何在下拉容器中使用过渡，使其缓慢显示，直到达到我想要的大小？

问题描述

我试图在我的下拉列表中使用过渡，所以当我点击它时，它会出现增加高度 2 秒，直到它达到我想要的高度（以同样的方式消失它），但是当我在我的dropdown-container 它不起作用，它立即向我显示全高度的下拉列表。有人可以帮助我吗？

var x=0;
/* 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 */
document.getElementById("btn-show-products").addEventListener("click", clickcont);

function clickcont(){
    if(x==0){
    openNav();
    x=1;
    }
    else{
    closeNav();
    x=0;
    }
}

function openNav() {
    document.getElementById("contenedor").style.height = "auto";
}

function closeNav() {
    document.getElementById("contenedor").style.height = "0";
}
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 {
    background-color: #262626;
    padding-left: 8px;
    height:0px;
    overflow-y:hidden;
    overflow-x:hidden;
    transition: 2s;
}

/* 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;}
}
<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" id="btn-show-products">Dropdown 
    <i class="fa fa-caret-down"></i>
  </button>
  <div class="dropdown-container" id="contenedor">
    <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>

标签： javascriptcss

解决方案

它不起作用，因为转换到 auto 高度时转换不起作用。尝试用某种类型的单位指定高度，你应该会很好。例如，这将起作用：

function openNav() {
    document.getElementById("contenedor").style.height = "100px";
}

祝你好运！

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