Element: className property
The className property of the
Element interface gets and sets the value of the class attribute
of the specified element.
Value
A string variable representing the class or space-separated classes of the current element.
Examples
const el = document.getElementById("item");
el.className = el.className === "active" ? "inactive" : "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"));
Note: The class is an HTML Attribute, while the
className is a DOM Property.
Specifications
| Specification |
|---|
| DOM Standard # ref-for-dom-element-classname① |
Browser compatibility
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