Question

我不知道如何为开启和关闭添加动画。我知道这个脚本不是那么好，但是我没有找到任何其他菜单脚本，当在drop block之外点击时可以自动关闭。谢谢。这是代码

/* 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');
      }
    }
  }
}

.dropbtn {
  background-color: #4CAF50;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}
.dropbtn:hover,
.dropbtn:focus {
  background-color: #3e8e41;
}
.dropdown {
  float: right;
  position: relative;
  display: inline-block;
}
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  right: 0;
  -webkit-transition: all 0.3s;
  -moz-transition: all 0.3s;
  -ms-transition: all 0.3s;
  -o-transition: all 0.3s;
  transition: all 0.3s;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  -webkit-animation-duration: 0.55s;
  animation-duration: 0.55s;
  -webkit-animation-timing-function: ease;
  animation-timing-function: ease;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}
.dropdown a:hover {
  background-color: #f1f1f1
}
.show {
  display: block;
  max-height: 200px;
  opacity: 1;
}

<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>

Answer 1

您尚未指定所需的转换类型，但您可以仅使用CSS来实现大多数转换。

在我下面的例子中，我使用了淡入/淡出。您已经定义了transition，但需要修改语法以使用opacity属性。另外，您设置了animation，这不是必需的。你还设置了元素的min-height，当关闭类时它会立即消失，所以我删除了它。

这是一个有效的例子：

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++) {
      dropdowns[i].classList.remove('show');
    }
  }
}

.dropbtn {
  background-color: #4CAF50;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}
.dropbtn:hover,
.dropbtn:focus {
  background-color: #3e8e41;
}
.dropdown {
  float: right;
  position: relative;
  display: inline-block;
}
.dropdown-content {
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  right: 0;
  -webkit-transition: opacity 0.5s;
  -moz-transition: opacity 0.5s;
  -ms-transition: opacity 0.5s;
  -o-transition: opacity 0.5s;
  transition: opacity 0.5s;
  overflow: hidden;
  opacity: 0;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}
.dropdown a:hover {
  background-color: #f1f1f1
}
.show {
  opacity: 1;
}

<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>

另请注意，您可以使用forEach()循环显示下拉列表，从而使JS更简洁：

if (!event.target.matches('.dropbtn')) {
  [].forEach.call(document.getElementsByClassName("dropdown-content"), function(dd) {
    dd.classList.remove('show');
  });
}

但请注意，这不适用于任何不支持ES2015的浏览器，例如。 IE8或更低版本。

在Javascript中动画div外观

1 个答案: