JavaScript, Get closest element by class. Mimics the jQuery's `.closest()` with pure JavaScript.

closest.js

define(function() {
    /**
     * Get the closest element of a given element by class
     *
     * Take an element (the firt param), and traverse the DOM upward from it
     * untill it hits the element with a given class name (second parameter).
     * This mimics jquery's `.closest()`.
     *
     * @param  {element} el    The element to start from
     * @param  {string}  clazz The class name
     * @return {element}       The closest element
     */
    return closestByClass = function(el, clazz) {
        while (el.className != clazz) {
            el = el.parentNode;
            if (!el) {
                return null;
            }
        }
        return el;
    }
});

below link is better . http://stackoverflow.com/questions/18663941/finding-closest-element-without-jquery/38994356#38994356

Hi matesnippets.
Thank you for your code. But I think line 14 should be: while(!el.classList.contains(clazz)) because if there are two classes, your code doesn't find the DOM object!!!