classList shim

getClassList.js

var getClassList = (function () {
    'use strict';

    var ClassList = {}, s = ' ';
    ClassList.add = function (cl) {
        var className = this.element.className,
            list = className.split(s);
        list.push(cl);
        this.element.className = list.join(s);
    };
    ClassList.remove = function (cl) {
        var className = this.element.className,
            list = className.split(s);
        for (var i = list.length - 1; i >= 0; i--) {
            if (list[i] === cl) {
                list.splice(i, 1);
            }
        }
        var newClassName = list.join(s);
        if (newClassName !== className) {
            this.element.className = newClassName;
        }
    };
    ClassList.contains = function (cl) {
        var className = this.element.className;
        return !!className && (s + className + s).indexOf(s + cl + s) >= 0;
    };

    return function (el) {
        if (el.classList) {
            return el.classList;
        } else {
            ClassList.element = el;
            return ClassList;
        }
    };
}());