用javascript写一个tab切换

可以使用以下代码实现tab切换：

HTML：

<div class="tab">
  <button class="tablinks" onclick="openTab(event, 'tab1')">Tab 1</button>
  <button class="tablinks" onclick="openTab(event, 'tab2')">Tab 2</button>
  <button class="tablinks" onclick="openTab(event, 'tab3')">Tab 3</button>
</div>

<div id="tab1" class="tabcontent">
  <h3>Tab 1 Content</h3>
  <p>Some text here...</p>
</div>

<div id="tab2" class="tabcontent">
  <h3>Tab 2 Content</h3>
  <p>Some text here...</p>
</div>

<div id="tab3" class="tabcontent">
  <h3>Tab 3 Content</h3>
  <p>Some text here...</p>
</div>

CSS：

.tab {
  overflow: hidden;
  border: 1px solid #ccc;
  background-color: #f1f1f1;
}

.tab button {
  background-color: inherit;
  float: left;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  transition: 0.3s;
}

.tab button:hover {
  background-color: #ddd;
}

.tab button.active {
  background-color: #ccc;
}

.tabcontent {
  display: none;
  padding: 6px 12px;
  border: 1px solid #ccc;
  border-top: none;
}

JavaScript：

function openTab(evt, tabName) {
  var i, tabcontent, tablinks;
  tabcontent = document.getElementsByClassName("tabcontent");
  for (i = 0; i < tabcontent.length; i++) {
    tabcontent[i].style.display = "none";
  }
  tablinks = document.getElementsByClassName("tablinks");
  for (i = 0; i < tablinks.length; i++) {
    tablinks[i].className = tablinks[i].className.replace(" active", "");
  }
  document.getElementById(tabName).style.display = "block";
  evt.currentTarget.className += " active";
}

在HTML中定义tab按钮和内容，CSS用于样式设置，JavaScript用于实现tab切换功能。在JavaScript中，openTab函数用于切换tab，通过获取tab内容和按钮的类名，来实现显示和隐藏tab内容以及按钮样式的变化。