Determine if an element has a CSS class with jQuery

Question

Use the hasClass method:

jQueryCollection.hasClass(className);

or

$(selector).hasClass(className);

The argument is (obviously) a string representing the class you are checking, and it returns a boolean (so it doesn't support chaining like most jQuery methods).

Note: If you pass a className argument that contains whitespace, it will be matched literally against the collection's elements' className string. So if, for instance, you have an element,

<span class="foo bar" />

then this will return true:

$('span').hasClass('foo bar')

and these will return false:

$('span').hasClass('bar foo')
$('span').hasClass('foo  bar')

from the FAQ

elem = $("#elemid");
if (elem.is (".class")) {
   // whatever
}

or:

elem = $("#elemid");
if (elem.hasClass ("class")) {
   // whatever
}

As for the negation, if you want to know if an element hasn't a class you can simply do as Mark said.

if (!currentPage.parent().hasClass('home')) { do what you want }

Without jQuery:

var hasclass=!!(' '+elem.className+' ').indexOf(' check_class ')+1;

Or:

function hasClass(e,c){
    return e&&(e instanceof HTMLElement)&&!!((' '+e.className+' ').indexOf(' '+c+' ')+1);
}
/*example of usage*/
var has_class_medium=hasClass(document.getElementsByTagName('input')[0],'medium');

This is WAY faster than jQuery!

In the interests of helping anyone who lands here but was actually looking for a jQuery free way of doing this:

element.classList.contains('your-class-name')