我正在尝试在HTML中使用选项卡。我正在使用来自W3SCHOOLS的教程。
以下是源代码。它可以正常工作,但我遇到的问题是默认选择第一个选项卡,在这个教程中缺失。我希望在页面加载时自动选择第一个选项卡,并自动显示其内容。
<!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;
-webkit-animation: fadeEffect 1s;
animation: fadeEffect 1s;
}
@-webkit-keyframes fadeEffect {
from {opacity: 0;}
to {opacity: 1;}
}
@keyframes fadeEffect {
from {opacity: 0;}
to {opacity: 1;}
}
</style>
<body>
<h3>Fade in Tabs</h3>
<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>
我应该在 JavaScript 中做出哪些改变来默认选择第一个选项卡?我在 for 循环中尝试了下面一行代码,但没有效果:
tablinks[0].className += " active";