Summary

className gets and sets the value of the class attribute of the specified element.

Syntax

var cName = elementNodeReference.className;
elementNodeReference.className = cName;
  • cName is a string variable representing the class or space-separated classes of the current element.

Example

let el = document.getElementById('item');

if (el.className === 'active'){
    el.className = 'inactive';
} else {
    el.className = 'active';
}

Notes

The name className is used for this property instead of class because of conflicts with the "class" keyword in many languages which are used to manipulate the DOM.

className can also be an instance of SVGAnimatedString if the element is an SVGElement. It is better to get/set the className of an element using Element.getAttribute and Element.setAttribute if you are dealing with SVG elements. However, take into account that Element.getAttribute returns null instead of "" if the element has an empty class attribute.

elm.setAttribute('class', elm.getAttribute('class'))

The class is an HTML Attribute, while the className is a DOM Property.

Specifications

Specification Status Comment
DOM
The definition of 'element.className' in that specification.
Living Standard  
DOM4
The definition of 'element.className' in that specification.
Obsolete  
Document Object Model (DOM) Level 2 HTML Specification
The definition of 'element.className' in that specification.
Obsolete Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support YesEdge Full support YesFirefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

See also