Utility methods for adding, removing, checking for and toggling classes in classNames.

classNameManipulation.js

var hasClass = function(el, c){
	return new RegExp("(\\s|^)" + c + "(\\s|$)", "g").test(el.className);
}

var addClass = function(el, c){
	if(!this.hasClass(el, c)) el.className += " " + c;
}

var removeClass = function(el, c){
	el.className = el.className.replace(new RegExp("(\\s|^)" + c + "(\\s|$)", "g"), " ").trim();
}

var toggleClass = function(el, c){
	if(this.hasClass(el, c))
		this.removeClass(el, c);
	else
		this.addClass(el, c);
}