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alignContent alignItems alignSelf animation animationDelay animationDirection animationDuration animationFillMode animationIterationCount animationName animationTimingFunction animationPlayState background backgroundAttachment backgroundColor backgroundImage backgroundPosition backgroundRepeat backgroundClip backgroundOrigin backgroundSize backfaceVisibility border borderBottom borderBottomColor borderBottomLeftRadius borderBottomRightRadius borderBottomStyle borderBottomWidth borderCollapse borderColor borderImage borderImageOutset borderImageRepeat borderImageSlice borderImageSource borderImageWidth borderLeft borderLeftColor borderLeftStyle borderLeftWidth borderRadius borderRight borderRightColor borderRightStyle borderRightWidth borderSpacing borderStyle borderTop borderTopColor borderTopLeftRadius borderTopRightRadius borderTopStyle borderTopWidth borderWidth bottom boxShadow boxSizing captionSide caretColor clear clip color columnCount columnFill columnGap columnRule columnRuleColor columnRuleStyle columnRuleWidth columns columnSpan columnWidth counterIncrement counterReset cursor direction display emptyCells filter flex flexBasis flexDirection flexFlow flexGrow flexShrink flexWrap cssFloat font fontFamily fontSize fontStyle fontVariant fontWeight fontSizeAdjust height isolation justifyContent left letterSpacing lineHeight listStyle listStyleImage listStylePosition listStyleType margin marginBottom marginLeft marginRight marginTop maxHeight maxWidth minHeight minWidth objectFit objectPosition opacity order orphans outline outlineColor outlineOffset outlineStyle outlineWidth overflow overflowX overflowY padding paddingBottom paddingLeft paddingRight paddingTop pageBreakAfter pageBreakBefore pageBreakInside perspective perspectiveOrigin position quotes resize right scrollBehavior tableLayout tabSize textAlign textAlignLast textDecoration textDecorationColor textDecorationLine textDecorationStyle textIndent textOverflow textShadow textTransform top transform transformOrigin transformStyle transition transitionProperty transitionDuration transitionTimingFunction transitionDelay unicodeBidi userSelect verticalAlign visibility width wordBreak wordSpacing wordWrap widows zIndex
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CSSStyleDeclaration JS Conversion

HTML DOM className Property

❮ Element Object


Set the class for a <div> element with id="myDIV":

document.getElementById("myDIV").className = "mystyle";
Try it Yourself »

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

className Yes Yes Yes Yes Yes


Return the className property:


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


Get the class name of the first <div> element in the document (if any):

var x = document.getElementsByTagName("DIV")[0].className;
Try it Yourself »


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;
Try it Yourself »


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;
Try it Yourself »


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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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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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") { = "30px";
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Toggle between two class names. This example looks for a "mystyle" class in <div>, and if it exist, it will be overwritten by "mystyle2":

function myFunction(){
  var x = document.getElementById("myDIV");
  // If "mystyle" exist, overwrite it with "mystyle2"
  if (x.className === "mystyle") {
    x.className = "mystyle2";
  } else {
    x.className = "mystyle";
Try it Yourself »


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 = "";
Try it Yourself »

Related Pages

CSS Tutorial: CSS Syntax

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