javascript - 努力为导航栏添加下拉效果

我一直在努力使我的导航栏在按下汉堡菜单时向下移动。我添加了CSS并进行了研究，但是我一直在努力理解为什么它不起作用。

我希望导航栏下拉并更改链接的不透明度。

我使用下面的答案来适应我的代码，但仍然遇到困难。

提前致谢。

function myFunction() {
  var x = document.getElementById("myLinks");
  if(x.className.indexOf('easein') > -1) {
    x.classList.remove('easein');
    x.classList.add('easeout')
  }
  else {
    x.classList.add('easein');
    x.classList.remove('easeout')
  }
}

.topnav {
        display: block;
        background-color: #fff;
        box-shadow: 1px 1px 16px 2px red;
        position: fixed;
        z-index: 45;
        right: 0;
        width: 100vw;
      }

      .topnav a#home {
          left: 0;
      }

      .topnav .myLinks {
        height: 0;
        opacity: 0;
        transition: all 1s ease-in-out;
        -webkit-transition: all 1s ease-in-out;
        -moz-transition: all 1s ease-in-out;
      }

      .topnav a {
        color: #0000a0;
        padding: 14px 16px;
        text-decoration: none;
        font-size: 17px;
        font-weight: 700;
        display: block;
      }

      .topnav a.icon {
        background: #fff;
        display: block;
        position: absolute;
        right: 0;
        top: 4vw;
        text-align: center;
      }

      .topnav a:hover {
        background-color: #ddd;
        color: black;
      }
      .fa {
          color: red;
      }

      #myLinks a{
        left: -10%;
        border-radius: 0;
        width: 100vw;
        margin: 0;
      }

      .topnav .myLinks.easein {
        height:500px;
        opacity: 1;
      }

      .topnav .myLinks.easeout {
        height:0px;
        opacity: 0;
      }

    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="topnav">
        <a href="#home" class="online">Logo</a>
        <div id="myLinks" class="myLinks">
            <a href="#news">Portal</a>
            <a href="#contact">Feedback</a>
            <a href="#about">Logout</a>
        </div>
        <a href="javascript:void(0);" class="icon" onclick="myFunction()">
            <i class="fa fa-bars"></i>
        </a>
        </div>

最佳答案

问题是您已将CSS属性显示设置为具有动画，我建议您将其更改为opacity和height，还请注意，我使用classList来添加/删除类，这是实现的功能您正在寻找：

function myFunction() {
  var x = document.getElementById("myLinks");
  if(x.className.indexOf('easein') > -1) {
    x.classList.remove('easein');
    x.classList.add('easeout')
  }
  else {
    x.classList.add('easein');
    x.classList.remove('easeout')
  }
}

.topnav {
  background-color: #fff;
  box-shadow: 1px 1px 16px 2px red;
  position: fixed;
  z-index: 20;
  right: 0;
  width: 100vw;
}

.topnav a#home {
    left: 0;
}

.topnav .myLinks {
  height: 0;
  opacity: 0;
  transition: all 1s ease-in-out;
  -webkit-transition: all 1s ease-in-out;
  -moz-transition: all 1s ease-in-out;
}

.topnav a {
  color: #0000a0;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
  display: block;
}

.topnav a.icon {
  background: #fff;
  display: block;
  position: absolute;
  right: 0;
  top: 4vw;
  text-align: center;
}

.topnav a:hover {
  background-color: #ddd;
  color: black;
}
.fa {
    color: red;
}

.myLinks a{
  width: 100vw;
}

.topnav .myLinks.easein {
  height:500px;
  opacity: 1;
}

.topnav .myLinks.easeout {
  height:0px;
  opacity: 0;
}

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="topnav">
    <a href="#home" class="online">Logo</a>
    <div id="myLinks" class="myLinks">
        <a href="#news">Portal</a>
        <a href="#contact">Feedback</a>
        <a href="#about">Logout</a>
    </div>
    <a href="javascript:void(0);" class="icon" onclick="myFunction()">
        <i class="fa fa-bars"></i>
    </a>
    </div>

关于javascript - 努力为导航栏添加下拉效果，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/61572837/