Add and remove classes to elements

AddandRemoveClasses.js

if (!String.prototype.trim) {
    String.prototype.trim = function () {
        return this.replace(/^\s+|\s+$/gi, '');
    }
}

function removeClass(el, className) {
    var curClass = el.className,
        re = new RegExp('\\b' + className + '\\b', 'g');
    
    if (curClass.test(re) === true) {
        curClass = curClass.replace(re, '').trim().replace(/\s+/gi, ' ');
    }

    el.className = curClass;
}

function addClass(el, className) {
    var curClass = el.className,
        re = new RegExp('\\b' + className + '\\b', 'g');
    
    if (curClass.test(re) === false) {
        curClass += (' ' + className).trim().replace(/\s+/gi, ' ');
    }

    el.className = curClass;
}