如何显示和隐藏？ [复制]答案

【问题标题】：How to Show and Hide? [duplicate]如何显示和隐藏？ [复制]
【发布时间】：2021-05-27 13:55:50
【问题描述】：

我在https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_toggle_hide_show找到了一个例子

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
#myDIV {
  width: 100%;
  padding: 50px 0;
  text-align: center;
  background-color: lightblue;
  margin-top: 20px;
}
</style>
</head>
<body>

<p>Click the "Try it" button to toggle between hiding and showing the DIV element:</p>

<button onclick="myFunction()">Try it</button>

<div id="myDIV">
This is my DIV element.
</div>

<p><b>Note:</b> The element will not take up any space when the display property set to "none".</p>

<script>
function myFunction() {
  var x = document.getElementById("myDIV");
  if (x.style.display === "none") {
    x.style.display = "block";
  } else {
    x.style.display = "none";
  }
}
</script>

</body>
</html>

但它是隐藏和显示。我应该如何修改它以便我可以做相反的事情？先显示然后隐藏切换？

【问题讨论】：

这能回答你的问题吗？ How do you create a hidden div that doesn't create a line break or horizontal space?

标签： javascript html show-hide

【解决方案1】：

首先，初始设置displa:none;，所以默认是隐藏的。

其次，在 if 语句 x.style.display === "" 中添加新规则，因为在第一次点击时是真的。

完整（工作）代码：

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
#myDIV {
  display: none;
  width: 100%;
  padding: 50px 0;
  text-align: center;
  background-color: lightblue;
  margin-top: 20px;
}
</style>
</head>
<body>

<p>Click the "Try it" button to toggle between hiding and showing the DIV element:</p>

<button onclick="myFunction()">Try it</button>

<div id="myDIV">
This is my DIV element.
</div>

<p><b>Note:</b> The element will not take up any space when the display property set to "none".</p>

<script>
function myFunction() {
  var x = document.getElementById("myDIV");
  if (x.style.display === "none" || x.style.display === "") {
    x.style.display = "block";
  } else {
    x.style.display = "none";
  }
}
</script>

</body>
</html>

编辑：更好的解决方案

使用getComputedStyle(x).display代替x.style.display，所以不需要和空字符串比较。

更新代码：

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
#myDIV {
  display: none;
  width: 100%;
  padding: 50px 0;
  text-align: center;
  background-color: lightblue;
  margin-top: 20px;
}
</style>
</head>
<body>

<p>Click the "Try it" button to toggle between hiding and showing the DIV element:</p>

<button onclick="myFunction()">Try it</button>

<div id="myDIV">
This is my DIV element.
</div>

<p><b>Note:</b> The element will not take up any space when the display property set to "none".</p>

<script>
function myFunction() {
  var x = document.getElementById("myDIV");
  if (getComputedStyle(x).display === "none") {
    x.style.display = "block";
  } else {
    x.style.display = "none";
  }
}
</script>

</body>
</html>

【讨论】：

【解决方案2】：

我建议在你的 css 中添加另一个类

.is-hidden
{
    display:none;
}

然后简单地在 is-hidden 和 nothing with 之间切换

 document.getElementById("#myDIV").classList.toggle("is-hidden");

如果要从隐藏的 div 开始，只需在定义处添加 is-hidden 类

<div id="myDIV" class="is-hidden">
   This is my DIV element.
</div>

【讨论】：