KP Joy KP Joy - 5 months ago 23
Javascript Question

TABS in HTML: Select first TAB by default

I am trying TABBING in HTML. I am using a tutorial from W3SCHOOLS (http://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_tabs_fade).

Following is the source code. It works fine but the problem I am facing is to select first tab by default which is missing in this tutorial. I want that first tab should be automatically selected when the page loads and the content of that should be displayed automatically.

<!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>


What change should I make in Javascript to select first tab by default. I tried following line inside for loop but did not work:

tablinks[0].className += " active";

Answer

In the anchor tag of first li add class=active and in the following div add display block div id=London class=tabcontent style=display:block

Here is a working JSfiddle