The HTML class attribute is used to specify a class for an HTML element. Multiple HTML elements can share the same class. The class is an attribute which specifies one or more class names for an HTML element. The class attribute can be used on any HTML element. The class name can be used by CSS and JavaScript to perform certain tasks for elements with the specified class name
How do you write a class in HTML?
Class selector selects elements with a specific class attribute. To select elements with a specific class, write a period (.)character, followed by the name of the class. You can also specify that only specific HTML elements should be affected by a class.
Using The class Attribute
The class attribute is often used to point to a class name in a style sheet. It can also be used by a JavaScript to access and manipulate elements with the specific class name. In the following example we have three <div> elements with a class attribute with the value of “city”. All of the three <div> elements will be styled equally according to the .city style definition in the head section:
Example
<!DOCTYPE html>
<html>
<head>
<style>
.city {
background-color: tomato;
color: white;
border: 2px solid black;
margin: 20px;
padding: 20px;
}
</style>
</head>
<body>
<div class="city">
<h2>London</h2>
<p>London is the capital of England.</p>
</div>
<div class="city">
<h2>Paris</h2>
<p>Paris is the capital of France.</p>
</div>
<div class="city">
<h2>Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>
</div>
</body>
</html>
In the following example we have two <span> elements with a class attribute with the value of “note”. Both <span> elements will be styled equally according to the .note style definition in the head section:
<!DOCTYPE html>
<html>
<head>
<style>
.note {
font-size: 120%;
color: red;
}
</style>
</head>
<body>
<h1>My <span class="note">Important</span> Heading</h1>
<p>This is some <span class="note">important</span> text.</p>
</body>
</html>
The Syntax For Class
To create a class; write a period (.) character, followed by a class name. Then, define the CSS properties within curly braces {}:
Example
Create a class named “city”:
<!DOCTYPE html>
<html>
<head>
<style>
.city {
background-color: tomato;
color: white;
padding: 10px;
}
</style>
</head>
<body>
<h2 class="city">London</h2>
<p>London is the capital of England.</p>
<h2 class="city">Paris</h2>
<p>Paris is the capital of France.</p>
<h2 class="city">Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>
</body>
</html>
Multiple Classes
HTML elements can belong to more than one class. To define multiple classes, separate the class names with a space, e.g. <div class=”city main”>. The element will be styled according to all the classes specified. In the following example, the first <h2> element belongs to both the city class and also to the main class, and will get the CSS styles from both of the classes:
Example:
<h2 class="city main">London</h2> <h2 class="city">Paris</h2> <h2 class="city">Tokyo</h2>
Different Elements Can Share Same Class
Different HTML elements can point to the same class name. In the following example, both <h2> and <p> points to the “city” class and will share the same style:
Example
<h2 class="city">Paris</h2> <p class="city">Paris is the capital of France</p>
Use of The class Attribute in JavaScript
The class name can also be used by JavaScript to perform certain tasks for specific elements. JavaScript can access elements with a specific class name with the getElementsByClassName() method:
Example
Click on a button to hide all elements with the class name “city”:
<script>
function myFunction() {
var x = document.getElementsByClassName("city");
for (var i = 0; i < x.length; i++) {
x[i].style.display = "none";
}
}
</script>
Other Examples
<!DOCTYPE html>
<html>
<head>
<style>
.headings{
color: lightgreen;
font-family: cursive;
background-color: black; }
</style>
</head>
<body>
<h1 class="headings">This is first heading</h1>
<h2 class="headings">This is Second heading</h2>
<h3 class="headings">This is third heading</h3>
<h4 class="headings">This is fourth heading</h4>
</body>
</html>
Supported Tags: It supports all HTML elements.
Example :
<!DOCTYPE html>
<html>
<head>
<style>
.country {
background-color: black;
color: white;
padding: 8px;
}
</style>
</head>
<body>
<h2 class="country">CHINA</h2>
<p>China has the largest population
in the world.</p>
<h2 class="country">INDIA</h2>
<p>India has the second largest
population in the world.</p>
<h2 class="country">UNITED STATES</h2>
<p>United States has the third largest
population in the world.</p>
</body>
</html>
Output:
