加载时打开标签（有序列表）？答案

【问题标题】：Open Tab(Ordered List) on load?加载时打开标签（有序列表）？
【发布时间】：2016-08-16 03:45:12
【问题描述】：

我正在按照示例使用 HTML 和 Javascript 制作选项卡式内容。链接在这里。

http://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_tabs

在这个示例中，我希望伦敦选项卡在页面加载后打开。我玩过 Javascript 代码中的 Active/Non active 类，但似乎无法弄清楚。

<!DOCTYPE html>
<html>
<style>
body {font-family: "Lato", sans-serif;}

ul.tab {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    border: 1px solid #ccc;
    background-color: #f1f1f1;
}

/* Float the list items side by side */
ul.tab li {float: left;}

/* Style the links inside the list items */
ul.tab li a {
    display: inline-block;
    color: black;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    transition: 0.3s;
    font-size: 17px;
}

/* Change background color of links on hover */
ul.tab li a:hover {
    background-color: #ddd;
}

/* Create an active/current tablink class */
ul.tab li a:focus, .active {
    background-color: #ccc;
}

/* Style the tab content */
.tabcontent {
    display: none;
    padding: 6px 12px;
    border: 1px solid #ccc;
    border-top: none;
}
</style>
<body>

<p>Click on the links inside the tabbed menu:</p>

<ul class="tab">
  <li><a href="#" class="tablinks" onclick="openCity(event, 'London')">London</a></li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Paris')">Paris</a></li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</a></li>
</ul>

<div id="London" class="tabcontent">
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" class="tabcontent">
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p>
</div>

<div id="Tokyo" class="tabcontent">
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

<script>
function openCity(evt, cityName) {
    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(cityName).style.display = "block";
    evt.currentTarget.className += " active";
}
</script>

</body>
</html>

【问题讨论】：

Cud 接受并支持您认为有用的答案。

标签： javascript jquery html css

【解决方案1】：

在页面加载后触发对该元素的自动点击：

document.addEventListener("DOMContentLoaded", function() {
  document.getElementById("default_city_link").click();
});

工作片段：

function openCity(evt, cityName) {
  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(cityName).style.display = "block";
  evt.currentTarget.className += " active";
}
document.addEventListener("DOMContentLoaded", function() {
  document.getElementById("default_city_link").click();
});

body {
  font-family: "Lato", sans-serif;
}
ul.tab {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  border: 1px solid #ccc;
  background-color: #f1f1f1;
}
/* Float the list items side by side */

ul.tab li {
  float: left;
}
/* Style the links inside the list items */

ul.tab li a {
  display: inline-block;
  color: black;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  transition: 0.3s;
  font-size: 17px;
}
/* Change background color of links on hover */

ul.tab li a:hover {
  background-color: #ddd;
}
/* Create an active/current tablink class */

ul.tab li a:focus,
.active {
  background-color: #ccc;
}
/* Style the tab content */

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

<p>Click on the links inside the tabbed menu:</p>

<ul class="tab">
  <li><a href="#" id="default_city_link" class="tablinks" onclick="openCity(event, 'London')">London</a>
  </li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Paris')">Paris</a>
  </li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</a>
  </li>
</ul>

<div id="London" class="tabcontent">
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" class="tabcontent">
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p>
</div>

<div id="Tokyo" class="tabcontent">
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

【讨论】：

【解决方案2】：

您可以在文档准备好后运行代码，如下所示：

<script>
$(document).ready(function(){
      openCity(event, 'London')
});


function openCity(evt, cityName) {
    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(cityName).style.display = "block";
    evt.currentTarget.className += " active";
}
</script>

【讨论】：

【解决方案3】：

您可以通过调用click() 函数在第一个标签上触发点击事件。 (http://www.w3schools.com/jsref/met_html_click.asp)

body {font-family: "Lato", sans-serif;}

ul.tab {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    border: 1px solid #ccc;
    background-color: #f1f1f1;
}

/* Float the list items side by side */
ul.tab li {float: left;}

/* Style the links inside the list items */
ul.tab li a {
    display: inline-block;
    color: black;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    transition: 0.3s;
    font-size: 17px;
}

/* Change background color of links on hover */
ul.tab li a:hover {
    background-color: #ddd;
}

/* Create an active/current tablink class */
ul.tab li a:focus, .active {
    background-color: #ccc;
}

/* Style the tab content */
.tabcontent {
    display: none;
    padding: 6px 12px;
    border: 1px solid #ccc;
    border-top: none;
}

<body>

<p>Click on the links inside the tabbed menu:</p>

<ul class="tab">
  <li><a href="#" class="tablinks" onclick="openCity(event, 'London')">London</a></li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Paris')">Paris</a></li>
  <li><a href="#" class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</a></li>
</ul>

<div id="London" class="tabcontent">
  <h3>London</h3>
  <p>London is the capital city of England.</p>
</div>

<div id="Paris" class="tabcontent">
  <h3>Paris</h3>
  <p>Paris is the capital of France.</p>
</div>

<div id="Tokyo" class="tabcontent">
  <h3>Tokyo</h3>
  <p>Tokyo is the capital of Japan.</p>
</div>

<script>
function openCity(evt, cityName) {
    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(cityName).style.display = "block";
    evt.currentTarget.className += " active";
}
  
document.getElementsByClassName('tablinks')[0].click();
</script>

</body>

【讨论】：