The Element.classList is a read-only property that returns a live DOMTokenList collection of the class attributes of the element. This can then be used to manipulate the class list.

Using classList is a convenient alternative to accessing an element's list of classes as a space-delimited string via element.className.


const elementClasses = elementNodeReference.classList;


A DOMTokenList representing the contents of the element's class attribute. If the class attribute is not set or empty, it returns an empty DOMTokenList, i.e. a DOMTokenList with the length property equal to 0.

The DOMTokenList itself is read-only, although you can modify it using the add() and remove() methods.


const div = document.createElement('div');
div.className = 'foo';

// our starting state: <div class="foo"></div>

// use the classList API to remove and add classes

// <div class="anotherclass"></div>

// if visible is set remove it, otherwise add it

// add/remove visible, depending on test conditional, i less than 10
div.classList.toggle("visible", i < 10 );


// add or remove multiple classes
div.classList.add("foo", "bar", "baz");
div.classList.remove("foo", "bar", "baz");

// add or remove multiple classes using spread syntax
const cls = ["foo", "bar"];

// replace class "foo" with class "bar"
div.classList.replace("foo", "bar");

Versions of Firefox before 26 do not implement the use of several arguments in the add/remove/toggle methods. See https://bugzilla.mozilla.org/show_bug.cgi?id=814014


The legacy onpropertychange event can be used to create a living classList mockup thanks to a Element.prototype.className property that fires the specified event once it is changed.

The following polyfill for both classList and DOMTokenList ensures full compliance (coverage) for all standard methods and properties of Element.prototype.classList for IE10-IE11 browsers plus nearly compliant behavior for IE 6-9. Check it out:

// 1. String.prototype.trim polyfill
if (!"".trim) String.prototype.trim = function(){ return this.replace(/^[\s]+|[\s]+$/g, ''); };
(function(window){"use strict"; // prevent global namespace pollution
if(!window.DOMException) (DOMException = function(reason){this.message = reason}).prototype = new Error;
var wsRE = /[\11\12\14\15\40]/, wsIndex = 0, checkIfValidClassListEntry = function(O, V) {
  if (V === "") throw new DOMException(
    "Failed to execute '" + O + "' on 'DOMTokenList': The token provided must not be empty." );
  if((wsIndex=V.search(wsRE))!==-1) throw new DOMException("Failed to execute '"+O+"' on 'DOMTokenList': " +
    "The token provided ('"+V[wsIndex]+"') contains HTML space characters, which are not valid in tokens.");
// 2. Implement the barebones DOMTokenList livelyness polyfill
if (typeof DOMTokenList !== "function") (function(window){
    var document = window.document, Object = window.Object, hasOwnProp = Object.prototype.hasOwnProperty;
    var defineProperty = Object.defineProperty, allowTokenListConstruction = 0, skipPropChange = 0;
    function DOMTokenList(){
        if (!allowTokenListConstruction) throw TypeError("Illegal constructor"); // internally let it through
    DOMTokenList.prototype.toString = DOMTokenList.prototype.toLocaleString = function(){return this.value};
    DOMTokenList.prototype.add = function(){
        a: for(var v=0, argLen=arguments.length,val="",ele=this[" uCL"],proto=ele[" uCLp"]; v!==argLen; ++v) {
            val = arguments[v] + "", checkIfValidClassListEntry("add", val);
            for (var i=0, Len=proto.length, resStr=val; i !== Len; ++i)
                if (this[i] === val) continue a; else resStr += " " + this[i];
            this[Len] = val, proto.length += 1, proto.value = resStr;
        skipPropChange = 1, ele.className = proto.value, skipPropChange = 0;
    DOMTokenList.prototype.remove = function(){
        for (var v=0, argLen=arguments.length,val="",ele=this[" uCL"],proto=ele[" uCLp"]; v !== argLen; ++v) {
            val = arguments[v] + "", checkIfValidClassListEntry("remove", val);
            for (var i=0, Len=proto.length, resStr="", is=0; i !== Len; ++i)
                if(is){ this[i-1]=this[i] }else{ if(this[i] !== val){ resStr+=this[i]+" "; }else{ is=1; } }
            if (!is) continue;
            delete this[Len], proto.length -= 1, proto.value = resStr;
        skipPropChange = 1, ele.className = proto.value, skipPropChange = 0;
    window.DOMTokenList = DOMTokenList;
    function whenPropChanges(){
        var evt = window.event, prop = evt.propertyName;
        if ( !skipPropChange && (prop==="className" || (prop==="classList" && !defineProperty)) ) {
            var target = evt.srcElement, protoObjProto = target[" uCLp"], strval = "" + target[prop];
            var tokens=strval.trim().split(wsRE), resTokenList=target[prop==="classList"?" uCL":"classList"];
            var oldLen = protoObjProto.length;
            a: for(var cI = 0, cLen = protoObjProto.length = tokens.length, sub = 0; cI !== cLen; ++cI){
                for(var innerI=0; innerI!==cI; ++innerI) if(tokens[innerI]===tokens[cI]) {sub++; continue a;}
                resTokenList[cI-sub] = tokens[cI];
            for (var i=cLen-sub; i < oldLen; ++i) delete resTokenList[i]; //remove trailing indexs
            if(prop !== "classList") return;
            skipPropChange = 1, target.classList = resTokenList, target.className = strval;
            skipPropChange = 0, resTokenList.length = tokens.length - sub;
    function polyfillClassList(ele){
        if (!ele || !("innerHTML" in ele)) throw TypeError("Illegal invocation");
        ele.detachEvent( "onpropertychange", whenPropChanges ); // prevent duplicate handler infinite loop
        allowTokenListConstruction = 1;
        try{ function protoObj(){} protoObj.prototype = new DOMTokenList(); }
        finally { allowTokenListConstruction = 0 }
        var protoObjProto = protoObj.prototype, resTokenList = new protoObj();
        a: for(var toks=ele.className.trim().split(wsRE), cI=0, cLen=toks.length, sub=0; cI !== cLen; ++cI){
            for (var innerI=0; innerI !== cI; ++innerI) if (toks[innerI] === toks[cI]) { sub++; continue a; }
            this[cI-sub] = toks[cI];
        protoObjProto.length = cLen-sub, protoObjProto.value = ele.className, protoObjProto[" uCL"] = ele;
        if (defineProperty) { defineProperty(ele, "classList", { // IE8 & IE9 allow defineProperty on the DOM
            enumerable:   1, get: function(){return resTokenList},
            configurable: 0, set: function(newVal){
                skipPropChange = 1, ele.className = protoObjProto.value = (newVal += ""), skipPropChange = 0;
                var toks = newVal.trim().split(wsRE), oldLen = protoObjProto.length;
                a: for(var cI = 0, cLen = protoObjProto.length = toks.length, sub = 0; cI !== cLen; ++cI){
                    for(var innerI=0; innerI!==cI; ++innerI) if(toks[innerI]===toks[cI]) {sub++; continue a;}
                    resTokenList[cI-sub] = toks[cI];
                for (var i=cLen-sub; i < oldLen; ++i) delete resTokenList[i]; //remove trailing indexs
        }); defineProperty(ele, " uCLp", { // for accessing the hidden prototype
            enumerable: 0, configurable: 0, writeable: 0, value: protoObj.prototype
        }); defineProperty(protoObjProto, " uCL", {
            enumerable: 0, configurable: 0, writeable: 0, value: ele
        }); } else { ele.classList=resTokenList, ele[" uCL"]=resTokenList, ele[" uCLp"]=protoObj.prototype; }
        ele.attachEvent( "onpropertychange", whenPropChanges );
    try { // Much faster & cleaner version for IE8 & IE9:
        // Should work in IE8 because Element.prototype instanceof Node is true according to the specs
        window.Object.defineProperty(window.Element.prototype, "classList", {
            enumerable: 1,   get: function(val){
                                 if (!hasOwnProp.call(this, "classList")) polyfillClassList(this);
                                 return this.classList;
            configurable: 0, set: function(val){this.className = val}
    } catch(e) { // Less performant fallback for older browsers (IE 6-8):
        window[" uCL"] = polyfillClassList;
        // the below code ensures polyfillClassList is applied to all current and future elements in the doc.
            '_*{x-uCLp:expression(!this.hasOwnProperty("classList")&&window[" uCL"](this))}' + //  IE6
            '[class]{x-uCLp/**/:expression(!this.hasOwnProperty("classList")&&window[" uCL"](this))}' //IE7-8
// 3. Patch in unsupported methods in DOMTokenList
(function(DOMTokenListProto, testClass){
    if (!DOMTokenListProto.item) DOMTokenListProto.item = function(i){
        function NullCheck(n) {return n===void 0 ? null : n} return NullCheck(this[i]);
    if (!DOMTokenListProto.toggle || testClass.toggle("a",0)!==false) DOMTokenListProto.toggle=function(val){
        if (arguments.length > 1) return (this[arguments[1] ? "add" : "remove"](val), !!arguments[1]);
        var oldValue = this.value;
        return (this.remove(oldValue), oldValue === this.value && (this.add(val), true) /*|| false*/);
    if (!DOMTokenListProto.replace || typeof testClass.replace("a", "b") !== "boolean")
        DOMTokenListProto.replace = function(oldToken, newToken){
            checkIfValidClassListEntry("replace", oldToken), checkIfValidClassListEntry("replace", newToken);
            var oldValue = this.value;
            return (this.remove(oldToken), this.value !== oldValue && (this.add(newToken), true));
    if (!DOMTokenListProto.contains) DOMTokenListProto.contains = function(value){
        for (var i=0,Len=this.length; i !== Len; ++i) if (this[i] === value) return true;
        return false;
    if (!DOMTokenListProto.forEach) DOMTokenListProto.forEach = function(f){
        if (arguments.length === 1) for (var i = 0, Len = this.length; i !== Len; ++i) f( this[i], i, this);
        else for (var i=0,Len=this.length,tArg=arguments[1]; i !== Len; ++i) f.call(tArg, this[i], i, this);
    if (!DOMTokenListProto.entries) DOMTokenListProto.entries = function(){
        var nextIndex = 0, that = this;
        return {next: function() {
            return nextIndex<that.length ? {value: [nextIndex, that[nextIndex++]], done: false} : {done: true};
    if (!DOMTokenListProto.values) DOMTokenListProto.values = function(){
        var nextIndex = 0, that = this;
        return {next: function() {
            return nextIndex<that.length ? {value: that[nextIndex++], done: false} : {done: true};
    if (!DOMTokenListProto.keys) DOMTokenListProto.keys = function(){
        var nextIndex = 0, that = this;
        return {next: function() {
            return nextIndex<that.length ? {value: nextIndex++, done: false} : {done: true};
})(window.DOMTokenList.prototype, window.document.createElement("div").classList);


The polyfill is limited in functionality. It's currently unable to polyfill out-of-document-elements (e.g. elements created by document.createElement before they are appended to a parent node) in IE6-7.

However, it should work just fine in IE9. A major discrepancy between the polyfilled version of classList and the W3 specs is that for IE6-8, there is no way to create an immutable object (an object whose properties cannot be directly modified). In IE9, however, it is possible through extending the prototype, freezing the visible object, and overwritting native property methods. However, such actions would not work in IE6-IE8 and, in IE9, slow the performance of the entire webpage to a snail's crawl, making these modifications completely impractical for this polyfill.

A minor note is that in IE6-7, this polyfill uses the window[" uCL"] property on the window object for communicating with the CSS expressions, the x-uCLp css property on all elements, and the element[" uCL"] property on all elements to allow garbage collection and boost performance. In all polyfilled browsers (IE6-9), an additional element[" uCLp"] property is added to element to ensure standards compliant prototyping, and a DOMTokenList[" uCL"] property is added to each element["classList"] object to ensure that the DOMTokenList is bounded to its own element.


Specification Status Comment
The definition of 'Element.classList' in that specification.
Living Standard Initial definition
The definition of 'Element.classList' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
classListChrome Full support 8Edge Full support 16
Full support 16
No support 12 — 16
Notes Not supported for SVG elements.
Firefox Full support 3.6IE Partial support 10
Partial support 10
Notes Not supported for SVG elements.
Opera Full support 11.5Safari Full support 6WebView Android Full support ≤37Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 11.5Safari iOS Full support 5Samsung Internet Android Full support 1.0
Multiple arguments for add() & remove()Chrome Full support 24Edge Full support 12Firefox Full support 26IE No support NoOpera Full support 15Safari Full support 7WebView Android Full support ≤37Chrome Android Full support 25Firefox Android Full support 26Opera Android Full support 14Safari iOS Full support 7Samsung Internet Android Full support 1.5
replace()Chrome Full support 61Edge Full support 17Firefox Full support 49IE No support NoOpera ? Safari No support NoWebView Android Full support 61Chrome Android Full support 61Firefox Android Full support 49Opera Android ? Safari iOS No support NoSamsung Internet Android Full support 8.0
toggle() method's second argumentChrome Full support 24Edge Full support 12Firefox Full support 24IE No support NoOpera Full support 15Safari Full support 7WebView Android Full support YesChrome Android Full support YesFirefox Android Full support 24Opera Android ? Safari iOS Full support 7Samsung Internet Android Full support Yes


Full support  
Full support
Partial support  
Partial support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.

See also