What is the "hasClass" function with plain JavaScript?
JavascriptDomJavascript Problem Overview
How do you do jQuery’s hasClass with plain ol’ JavaScript? For example,
<body class="foo thatClass bar">
What’s the JavaScript way to ask if <body> has thatClass?
Javascript Solutions
Solution 1 - Javascript
Simply use classList.contains():
if (document.body.classList.contains('thatClass')) {
// do some stuff
}
Other uses of classList:
document.body.classList.add('thisClass');
// $('body').addClass('thisClass');
document.body.classList.remove('thatClass');
// $('body').removeClass('thatClass');
document.body.classList.toggle('anotherClass');
// $('body').toggleClass('anotherClass');
Browser Support:
- Chrome 8.0
- Firefox 3.6
- IE 10
- Opera 11.50
- Safari 5.1
Solution 2 - Javascript
You can check whether element.className matches /\bthatClass\b/.
\b matches a word break.
Or, you can use jQuery's own implementation:
var className = " " + selector + " ";
if ( (" " + element.className + " ").replace(/[\n\t]/g, " ").indexOf(" thatClass ") > -1 )
To answer your more general question, you can look at jQuery's source code on github or at the source for hasClass specifically in this source viewer.
Solution 3 - Javascript
The most effective one liner that
- returns a boolean (as opposed to Orbling's answer)
- Does not return a false positive when searching for
thisClasson an element that hasclass="thisClass-suffix". - is compatible with every browser down to at least IE6
function hasClass( target, className ) {
return new RegExp('(\\s|^)' + className + '(\\s|$)').test(target.className);
}
Solution 4 - Javascript
// 1. Use if for see that classes:
if (document.querySelector(".section-name").classList.contains("section-filter")) {
alert("Grid section");
// code...
}
<!--2. Add a class in the .html:-->
<div class="section-name section-filter">...</div>
Solution 5 - Javascript
The attribute that stores the classes in use is className.
So you can say:
if (document.body.className.match(/\bmyclass\b/)) {
....
}
If you want a location that shows you how jQuery does everything, I would suggest:
Solution 6 - Javascript
Element.matches()
Instead of $(element).hasClass('example') in jQuery, you can use element.matches('.example') in plain JavaScript:
if (element.matches('.example')) {
// Element has example class ...
}
Solution 7 - Javascript
hasClass function:
HTMLElement.prototype.hasClass = function(cls) {
var i;
var classes = this.className.split(" ");
for(i = 0; i < classes.length; i++) {
if(classes[i] == cls) {
return true;
}
}
return false;
};
addClass function:
HTMLElement.prototype.addClass = function(add) {
if (!this.hasClass(add)){
this.className = (this.className + " " + add).trim();
}
};
removeClass function:
HTMLElement.prototype.removeClass = function(remove) {
var newClassName = "";
var i;
var classes = this.className.replace(/\s{2,}/g, ' ').split(" ");
for(i = 0; i < classes.length; i++) {
if(classes[i] !== remove) {
newClassName += classes[i] + " ";
}
}
this.className = newClassName.trim();
};
Solution 8 - Javascript
I use a simple/minimal solution, one line, cross browser, and works with legacy browsers as well:
/\bmyClass/.test(document.body.className) // notice the \b command for whole word 'myClass'
This method is great because does not require polyfills and if you use them for classList it's much better in terms of performance. At least for me.
Update: I made a tiny polyfill that's an all round solution I use now:
function hasClass(element,testClass){
if ('classList' in element) { return element.classList.contains(testClass);
} else { return new Regexp(testClass).exec(element.className); } // this is better
//} else { return el.className.indexOf(testClass) != -1; } // this is faster but requires indexOf() polyfill
return false;
}
For the other class manipulation, see the complete file here.
Solution 9 - Javascript
a good solution for this is to work with classList and contains.
i did it like this:
... for ( var i = 0; i < container.length; i++ ) {
if ( container[i].classList.contains('half_width') ) { ...
So you need your element and check the list of the classes. If one of the classes is the same as the one you search for it will return true if not it will return false!
Solution 10 - Javascript
Use something like:
Array.prototype.indexOf.call(myHTMLSelector.classList, 'the-class');
Solution 11 - Javascript
if (document.body.className.split(/\s+/).indexOf("thatClass") !== -1) {
// has "thatClass"
}
Solution 12 - Javascript
This 'hasClass' function works in IE8+, FireFox and Chrome:
hasClass = function(el, cls) {
var regexp = new RegExp('(\\s|^)' + cls + '(\\s|$)'),
target = (typeof el.className === 'undefined') ? window.event.srcElement : el;
return target.className.match(regexp);
}
[Updated Jan'2021] A better way:
hasClass = (el, cls) => {
[...el.classList].includes(cls); //cls without dot
};
Solution 13 - Javascript
Well all of the above answers are pretty good but here is a small simple function I whipped up. It works pretty well.
function hasClass(el, cn){
var classes = el.classList;
for(var j = 0; j < classes.length; j++){
if(classes[j] == cn){
return true;
}
}
}
Solution 14 - Javascript
What do you think about this approach?
<body class="thatClass anotherClass"> </body>
var bodyClasses = document.querySelector('body').className;
var myClass = new RegExp("thatClass");
var trueOrFalse = myClass.test( bodyClasses );