Add Class to HTML Tag On Click using JavaScript

In this tutorial we will see how to Add Class to HTML Tag On Click using JavaScript. The getElementById() Method and HTML DOM className Property are used for this purpose.

HTML Code

HTML Code is given below, This code contains a paragraph element and a button element.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Add Class to HTML Tag On Click using JavaScript</title>
</head>
<body>
<p id="main">Add my new class!</p>
<button onclick="addClass()">Add Class</button> 
</body>
</html>

CSS Code

CSS Code is given below, In this code we have defined CSS properties for our class 'text', which will be added to html tag using JavaScript.

.text
 { background-color: green;
   color: white;
   padding: 20px 10px;
 }

getElementById() Method

The getElementById() Method is used to get or select or target the HTML element with a specified value of Id attribute.

In this example the id of paragraph element is 'main'. This id is used to target or select the paragraph element.

The getElementById() Method is supported by all major browsers.

className Property

The JavaScript className Property sets or returns the class name of an element.

The JavaScript className Property is supported by all major browsers.

JavaScript Code

In this example getElementById method is used to select the paragraph tag. Then className property is used to add the class to the paragraph tag.

onclick event is used to trigger the main function (addClass()) which performs this task.

Take a look at the code given below.

<script>
function addClass()
 {
   document.getElementById("main").className = "text";
 }
</script>

Demo

Video Tutorial

Watch video tutorial on how to Add Class to HTML Tag On Click using JavaScript.

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