Example
Set the class for a <div> element with id="myDIV":
document.getElementById("myDIV").className = "mystyle";
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More "Try it Yourself" examples below.
Definition and Usage
The className property sets or returns the class name of an element (the value of an element's class attribute).
Tip: A similar property to className is the classList property.
Browser Support
| Property | |||||
|---|---|---|---|---|---|
| className | Yes | Yes | Yes | Yes | Yes |
Syntax
Return the className property:
HTMLElementObject.className
Set the className property:
HTMLElementObject.className=class
Property Values
| Value | Description |
|---|---|
| class | Specifies the class name of an element. To apply multiple classes, separate them with spaces, like "test demo" |
Technical Details
| Return Value: | A String, representing the class, or a space-separated list of classes, of an element |
|---|
More Examples
Example
Get the class name of the first <div> element in the document (if any):
var x = document.getElementsByTagName("DIV")[0].className;
The result of x will be:
mystyle
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Example
Other examples on how to get the class name of an element:
var x = document.getElementsByClassName("mystyle")[0].className;
var y =
document.getElementById("myDIV").className;
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Example
Get the class names of an element with multiple classes:
<div id="myDIV" class="mystyle test example">I am a DIV element</div>
var x = document.getElementById("myDIV").className;
The result of x will be:
mystyle text example
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Example
Overwriting an existing class name with a new one:
<div id="myDIV" class="mystyle">I am a DIV element</div>
document.getElementById("myDIV").className = "newClassName";
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Example
To add a class to an element, without overwriting existing values, insert a space and the new class name:
document.getElementById("myDIV").className += " anotherClass";
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Example
If there's a class of "mystyle" in an element with id="myDIV", change its font-size:
var x = document.getElementById("myDIV");
if (x.className ===
"mystyle") {
x.style.fontSize = "30px";
}
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Example
Toggle between class names on different scroll positions - When the user scrolls down 50 pixels from the top, the class name "test" will be added to an element (and removed when scrolled up again).
window.onscroll = function() {myFunction()};
function myFunction() {
if (document.body.scrollTop > 50) {
document.getElementById("myP").className = "test";
}
else {
document.getElementById("myP").className
= "";
}
}
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Related Pages
CSS Tutorial: CSS Selectors
CSS Reference: CSS .class Selector
HTML DOM Reference: HTML DOM classList Property
HTML DOM Reference: HTML DOM getElementsByClassName() Method
HTML DOM Reference: HTML DOM Style Object
< Element Object