javascript - 如何在此 javascript 中启用默认选择的第一个选项卡？

Question

该代码创建了 3 个内容选项卡，如何在页面加载时默认选择第一个选项卡，之后，它应该按预期运行。用户应该能够点击任何其他选项卡，但在开始时，第一个选项卡应该默认打开。

function openCity(evt, cityName) {
  var i, x, tablinks;
  x = document.getElementsByClassName("city");
  for (i = 0; i < x.length; i++) {
    x[i].style.display = "none";
  }
  tablinks = document.getElementsByClassName("tablink");
  for (i = 0; i < x.length; i++) {
    tablinks[i].className = tablinks[i].className.replace(" w3-border-red", "");
  }
  document.getElementById(cityName).style.display = "block";
  evt.currentTarget.firstElementChild.className += " w3-border-red";
}

<div class="w3-container">
  <h2>Tabs in a Grid</h2>

  <div class="w3-row">
    <a href="javascript:void(0)" onclick="openCity(event, 'London');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding">London</div>
    </a>
    <a href="javascript:void(0)" onclick="openCity(event, 'Paris');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding">Paris</div>
    </a>
    <a href="javascript:void(0)" onclick="openCity(event, 'Tokyo');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding">Tokyo</div>
    </a>
  </div>

  <div id="London" class="w3-container city" style="display:none">
    <h2>London</h2>
    <p>London is the capital city of England.</p>
  </div>

  <div id="Paris" class="w3-container city" style="display:none">
    <h2>Paris</h2>
    <p>Paris is the capital of France.</p>
  </div>

  <div id="Tokyo" class="w3-container city" style="display:none">
    <h2>Tokyo</h2>
    <p>Tokyo is the capital of Japan.</p>
  </div>
</div>

Answer 1

您只需要在第一个选项卡的 html 中添加 selected class 并从相应的详细信息 Pane 中删除 display:none。

function openCity(evt, cityName) {
  var i, x, tablinks;
  x = document.getElementsByClassName("city");
  for (i = 0; i < x.length; i++) {
     x[i].style.display = "none";
  }
  tablinks = document.getElementsByClassName("tablink");
  for (i = 0; i < x.length; i++) {
     tablinks[i].className = tablinks[i].className.replace(" w3-border-red", "");
  }
  document.getElementById(cityName).style.display = "block";
  evt.currentTarget.firstElementChild.className += " w3-border-red";
}

<div class="w3-container">
  <h2>Tabs in a Grid</h2>

  <div class="w3-row">
    <a href="javascript:void(0)" onclick="openCity(event, 'London');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding w3-border-red">London</div>
    </a>
    <a href="javascript:void(0)" onclick="openCity(event, 'Paris');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding">Paris</div>
    </a>
    <a href="javascript:void(0)" onclick="openCity(event, 'Tokyo');">
      <div class="w3-third tablink w3-bottombar w3-hover-light-grey w3-padding">Tokyo</div>
    </a>
  </div>

  <div id="London" class="w3-container city">
    <h2>London</h2>
    <p>London is the capital city of England.</p>
  </div>

  <div id="Paris" class="w3-container city" style="display:none">
    <h2>Paris</h2>
    <p>Paris is the capital of France.</p> 
  </div>

  <div id="Tokyo" class="w3-container city" style="display:none">
    <h2>Tokyo</h2>
    <p>Tokyo is the capital of Japan.</p>
  </div>
</div>