Check if an element contains a class in JavaScript?
JavascriptHtmlCssDomJavascript Problem Overview
Using plain JavaScript (not jQuery), Is there any way to check if an element contains a class?
Currently, I'm doing this:
var test = document.getElementById("test");
var testClass = test.className;
switch (testClass) {
case "class1":
test.innerHTML = "I have class1";
break;
case "class2":
test.innerHTML = "I have class2";
break;
case "class3":
test.innerHTML = "I have class3";
break;
case "class4":
test.innerHTML = "I have class4";
break;
default:
test.innerHTML = "";
}
<div id="test" class="class1"></div>
The issue is that if I change the HTML to this...
<div id="test" class="class1 class5"></div>
...there's no longer an exact match, so I get the default output of nothing (""
). But I still want the output to be I have class1
because the <div>
still contains the .class1
class.
Javascript Solutions
Solution 1 - Javascript
Use element.classList
.contains
method:
element.classList.contains(class);
This works on all current browsers and there are polyfills to support older browsers too.
Alternatively, if you work with older browsers and don't want to use polyfills to fix them, using indexOf
is correct, but you have to tweak it a little:
function hasClass(element, className) {
return (' ' + element.className + ' ').indexOf(' ' + className+ ' ') > -1;
}
Otherwise you will also get true
if the class you are looking for is part of another class name.
jQuery uses a similar (if not the same) method.
Applied to the example:
As this does not work together with the switch statement, you could achieve the same effect with this code:
var test = document.getElementById("test"),
classes = ['class1', 'class2', 'class3', 'class4'];
test.innerHTML = "";
for(var i = 0, j = classes.length; i < j; i++) {
if(hasClass(test, classes[i])) {
test.innerHTML = "I have " + classes[i];
break;
}
}
It's also less redundant ;)
Solution 2 - Javascript
The easy and effective solution is trying .contains method.
test.classList.contains(testClass);
Solution 3 - Javascript
In modern browsers, you can just use the contains
method of Element.classList
:
testElement.classList.contains(className)
Demo
<div id="test" class="main main-content content"></div>
var testElement = document.getElementById('test');
console.log({
'main' : testElement.classList.contains('main'),
'cont' : testElement.classList.contains('cont'),
'content' : testElement.classList.contains('content'),
'main-cont' : testElement.classList.contains('main-cont'),
'main-content' : testElement.classList.contains('main-content')
});
Supported browsers
(from CanIUse.com)
Polyfill
If you want to use Element.classList
but you also want to support older browsers, consider using this polyfill by Eli Grey.
Solution 4 - Javascript
Element.matches()
element.matches(selectorString)
According to MDN Web Docs:
> The Element.matches()
method returns true
if the element would be selected by the specified selector string; otherwise, returns false
.
Therefore, you can use Element.matches()
to determine if an element contains a class.
const element = document.querySelector('#example');
console.log(element.matches('.foo')); // true
<div id="example" class="foo bar"></div>
Solution 5 - Javascript
Since he wants to use switch(), I'm surprised no one has put this forth yet:
var test = document.getElementById("test");
var testClasses = test.className.split(" ");
test.innerHTML = "";
for(var i=0; i<testClasses.length; i++) {
switch(testClasses[i]) {
case "class1": test.innerHTML += "I have class1<br/>"; break;
case "class2": test.innerHTML += "I have class2<br/>"; break;
case "class3": test.innerHTML += "I have class3<br/>"; break;
case "class4": test.innerHTML += "I have class4<br/>"; break;
default: test.innerHTML += "(unknown class:" + testClasses[i] + ")<br/>";
}
}
Solution 6 - Javascript
Here is a little snippet If you’re trying to check wether element contains a class, without using jQuery.
function hasClass(element, className) {
return element.className && new RegExp("(^|\\s)" + className + "(\\s|$)").test(element.className);
}
This accounts for the fact that element might contain multiple class names separated by space.
OR
You can also assign this function to element prototype.
Element.prototype.hasClass = function(className) {
return this.className && new RegExp("(^|\\s)" + className + "(\\s|$)").test(this.className);
};
And trigger it like this (very similar to jQuery’s .hasClass()
function):
document.getElementById('MyDiv').hasClass('active');
Solution 7 - Javascript
This is a little old, but maybe someone will find my solution helpfull:
// Fix IE's indexOf Array
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function (searchElement) {
if (this == null) throw new TypeError();
var t = Object(this);
var len = t.length >>> 0;
if (len === 0) return -1;
var n = 0;
if (arguments.length > 0) {
n = Number(arguments[1]);
if (n != n) n = 0;
else if (n != 0 && n != Infinity && n != -Infinity) n = (n > 0 || -1) * Math.floor(Math.abs(n));
}
if (n >= len) return -1;
var k = n >= 0 ? n : Math.max(len - Math.abs(n), 0);
for (; k < len; k++) if (k in t && t[k] === searchElement) return k;
return -1;
}
}
// add hasClass support
if (!Element.prototype.hasClass) {
Element.prototype.hasClass = function (classname) {
if (this == null) throw new TypeError();
return this.className.split(' ').indexOf(classname) === -1 ? false : true;
}
}
Solution 8 - Javascript
className
is just a string so you can use the regular indexOf function to see if the list of classes contains another string.
Solution 9 - Javascript
A simplified oneliner:1
function hasClassName(classname,id) {
return String ( ( document.getElementById(id)||{} ) .className )
.split(/\s/)
.indexOf(classname) >= 0;
}
1 indexOf
for arrays is not supported by IE (ofcourse). There are plenty of monkey patches to be found on the net for that.
Solution 10 - Javascript
I know there a lot of answers but most of these are for additional functions and additional classes. This is the one I personally use; much cleaner and much less lines of code!
if( document.body.className.match('category-page') ) {
console.log('yes');
}
Solution 11 - Javascript
This question is pretty solidly answered by element.classList.contains()
, but people got pretty extravagant with their answers and made some bold claims, so I ran a benchmark.
Remember that each test is doing 1000 iterations, so most of these are still very fast. Unless you rely extensively on this for a specific operation, you won't see a performance difference.
I ran some tests with basically every way to do this. On my machine, (Win 10, 24gb, i7-8700), classList.contains performed super well. So did className.split(' ') which is effectively the same.
The winner though is classList.contains()
. If you're not checking for classList to be undefined
, ~(' ' + v.className + ' ').indexOf(' c' + i + ' ')
creeps ahead 5-15%
Solution 12 - Javascript
I've created a prototype method which uses classList
, if possible, else resorts to indexOf
:
<p class='a b c'>This is a <b>test</b> string</p>
<svg xmlns="http://www.w3.org/2000/svg" width="100px" height="50px">
<text x="10" y="20" class='a'>SVG Text Example</text>
</svg>
Element.prototype.hasClass = Element.prototype.hasClass ||
function(classArr){
var hasClass = 0,
className = this.getAttribute('class');
if( this == null || !classArr || !className ) return false;
if( !(classArr instanceof Array) )
classArr = classArr.split(' ');
for( var i in classArr )
// this.classList.contains(classArr[i]) // for modern browsers
if( className.split(classArr[i]).length > 1 )
hasClass++;
return hasClass == classArr.length;
};
///////////////////////////////
// TESTS (see browser's console when inspecting the output)
var elm1 = document.querySelector('p');
var elm2 = document.querySelector('b');
var elm3 = elm1.firstChild; // textNode
var elm4 = document.querySelector('text'); // SVG text
console.log( elm1, ' has class "a": ', elm1.hasClass('a') );
console.log( elm1, ' has class "b": ', elm1.hasClass('b') );
console.log( elm1, ' has class "c": ', elm1.hasClass('c') );
console.log( elm1, ' has class "d": ', elm1.hasClass('d') );
console.log( elm1, ' has class "a c": ', elm1.hasClass('a c') );
console.log( elm1, ' has class "a d": ', elm1.hasClass('a d') );
console.log( elm1, ' has class "": ', elm1.hasClass('') );
console.log( elm2, ' has class "a": ', elm2.hasClass('a') );
// console.log( elm3, ' has class "a": ', elm3.hasClass('a') );
console.log( elm4, ' has class "a": ', elm4.hasClass('a') );
Test page
Solution 13 - Javascript
To check if an element contains a class, you use the contains() method of the classList property of the element:*
element.classList.contains(className);
*Suppose you have the following
<div class="secondary info">Item</div>*
To check if the
const div = document.querySelector('div');
div.classList.contains('secondary'); // true
The following returns false because the
const div = document.querySelector('div');
div.classList.contains('error'); // false
Solution 14 - Javascript
Here's a case-insensitive trivial solution:
function hasClass(element, classNameToTestFor) {
var classNames = element.className.split(' ');
for (var i = 0; i < classNames.length; i++) {
if (classNames[i].toLowerCase() == classNameToTestFor.toLowerCase()) {
return true;
}
}
return false;
}
Solution 15 - Javascript
-
Felix's trick of adding spaces to flank the className and the string you're searching for is the right approach to determining whether the elements has the class or not.
-
To have different behaviour according to the class, you may use function references, or functions, within a map:
function fn1(element){ /* code for element with class1 */ } function fn2(element){ /* code for element with class2 */ } function fn2(element){ /* code for element with class3 */ } var fns={'class1': fn1, 'class2': fn2, 'class3': fn3}; for(var i in fns) { if(hasClass(test, i)) { fns[i](test); } }
- for(var i in fns) iterates through the keys within the fns map.
- Having no break after fnsi allows the code to be executed whenever there is a match - so that if the element has, f.i., class1 and class2, both fn1 and fn2 will be executed.
- The advantage of this approach is that the code to execute for each class is arbitrary, like the one in the switch statement; in your example all the cases performed a similar operation, but tomorrow you may need to do different things for each.
- You may simulate the default case by having a status variable telling whether a match was found in the loop or not.
Solution 16 - Javascript
If the element only has one class name you can quickly check it by getting the class attribute. The other answers are much more robust but this certainly has it's use cases.
if ( element.getAttribute('class') === 'classname' ) {
}
Solution 17 - Javascript
See this Codepen link for faster and easy way of checking an element if it has a specific class using vanilla JavaScript~!
function hasClass(element, cls) {
return (' ' + element.className + ' ').indexOf(' ' + cls + ' ') > -1;
}
Solution 18 - Javascript
This is supported on IE8+.
First we check if classList
exists if it does we can use the contains
method which is supported by IE10+. If we are on IE9 or 8 it falls back to using a regex, which is not as efficient but is a concise polyfill.
if (el.classList) {
el.classList.contains(className);
} else {
new RegExp('(^| )' + className + '( |$)', 'gi').test(el.className);
}
Alternatively if you are compiling with babel you can simply use:
el.classList.contains(className);
Solution 19 - Javascript
I would Poly fill the classList functionality and use the new syntax. This way newer browser will use the new implementation (which is much faster) and only old browsers will take the performance hit from the code.
Solution 20 - Javascript
This is a bit off, but if you have an event that triggers switch, you can do without classes:
<div id="classOne1"></div>
<div id="classOne2"></div>
<div id="classTwo3"></div>
You can do
$('body').click( function() {
switch ( this.id.replace(/[0-9]/g, '') ) {
case 'classOne': this.innerHTML = "I have classOne"; break;
case 'classTwo': this.innerHTML = "I have classTwo"; break;
default: this.innerHTML = "";
}
});
.replace(/[0-9]/g, '')
removes digits from id
.
It is a bit hacky, but works for long switches without extra functions or loops
Solution 21 - Javascript
Using the classList is also ideal
HTML
<div id="box" class="myClass"></div>
JavaScript
const element = document.querySelector("#box");
element.classList.contains("myClass");
Solution 22 - Javascript
As the accepted answer suggests, Element.className
returns a string, so you can easily check if a class exists by using the indexOf()
method:
element.className.indexOf('animated') > -1
If you are interested in the performance difference between indexOf
vs classList.contains
, using indexOf
seems to be slightly faster. I did a quick benchmark performance test to check that. Here are my findings: ClassName.indexOf vs ClassList.contains.
Solution 23 - Javascript
Try this one:
document.getElementsByClassName = function(cl) {
var retnode = [];
var myclass = new RegExp('\\b'+cl+'\\b');
var elem = this.getElementsByTagName('*');
for (var i = 0; i < elem.length; i++) {
var classes = elem[i].className;
if (myclass.test(classes)) retnode.push(elem[i]);
}
return retnode;
};
Solution 24 - Javascript
I think that perfect solution will be this
if ($(this).hasClass("your_Class"))
alert("positive");
else
alert("Negative");
Solution 25 - Javascript
in which element is currently the class '.bar' ? Here is another solution but it's up to you.
var reg = /Image/g, // regexp for an image element
query = document.querySelector('.bar'); // returns [object HTMLImageElement]
query += this.toString(); // turns object into a string
if (query.match(reg)) { // checks if it matches
alert('the class .bar is attached to the following Element:\n' + query);
}
Of course this is only a lookup for 1 simple element <img>
(/Image/g
) but you can put all in an array like <li>
is /LI/g
, <ul>
= /UL/g
etc.
Solution 26 - Javascript
Just to add to the answer for people trying to find class names within inline SVG elements.
Change the hasCLass()
function to:
function hasClass(element, cls) {
return (' ' + element.getAttribute('class') + ' ').indexOf(' ' + cls + ' ') > -1;
}
Instead of using the className
property you'll need to use the getAttribute()
method to grab the class name.
Solution 27 - Javascript
I created these functions for my website, I use only vanilla javascript, maybe it will help someone. First I created a function to get any HTML element:
//return an HTML element by ID, class or tag name
var getElement = function(selector) {
var elements = [];
if(selector[0] == '#') {
elements.push(document.getElementById(selector.substring(1, selector.length)));
} else if(selector[0] == '.') {
elements = document.getElementsByClassName(selector.substring(1, selector.length));
} else {
elements = document.getElementsByTagName(selector);
}
return elements;
}
Then the function that recieve the class to remove and the selector of the element:
var hasClass = function(selector, _class) {
var elements = getElement(selector);
var contains = false;
for (let index = 0; index < elements.length; index++) {
const curElement = elements[index];
if(curElement.classList.contains(_class)) {
contains = true;
break;
}
}
return contains;
}
Now you can use it like this:
hasClass('body', 'gray')
hasClass('#like', 'green')
hasClass('.button', 'active')
Hope it will help.
Solution 28 - Javascript
Tip: Try to remove dependencies of jQuery in your projects as much as you can - VanillaJS.
document.firstElementChild
returns <html>
tag then the classList
attribute returns all classes added to it.
if(document.firstElementChild.classList.contains("your-class")){
// <html> has 'your-class'
} else {
// <html> doesn't have 'your-class'
}
Solution 29 - Javascript
Since .className
is a string, you can use the string includes()
method to check if your .className
includes your class name:
element.className.includes("class1")