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 SVGElement if the element is an SVGAnimatedString. It is better to get/set the className of an element using Element.getAttribute and Element.setAttribute if you are dealing with SVG elements.

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

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes Yes Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes Yes Yes Yes Yes

See also