How can I check in JavaScript if a DOM element contains a class?

Question

How can I check in JavaScript if a DOM element contains a class?

I tried the following code, but for some reason it doesn\'t work...

if (document.get         


        

Answer 1

The property you need is className, not class. Also, an element can have many classes, so if you want to test if it has a particular class you need to do something like the following:

function hasClass(el, clss) {
    return el.className && new RegExp("(^|\\s)" +
           clss + "(\\s|$)").test(el.className);
}

var element = document.getElementById('element');
if ( hasClass(element, "class_one") ) {
    // Do stuff here
}

UPDATE

Modern browsers (pretty much everything major except IE <= 9) support a classList property, as mentioned in @Dropped.on.Caprica's answer. It therefore makes sense to use this where available. Here's some example code that detects whether classList is supported by the browser and falls back to the regex-based code otherwise:

var hasClass = (typeof document.documentElement.classList == "undefined") ?
    function(el, clss) {
        return el.className && new RegExp("(^|\\s)" +
               clss + "(\\s|$)").test(el.className);
    } :
    function(el, clss) {
        return el.classList.contains(clss);
    };