addClass(), removeClass(), hasClass()

elementAddClass(el, className); elementRemoveClass(el, className); elementHasClass(el, className)

by Yury

JavaScript

function elementAddClass(el, className) {
    var add_className = className || false;
    if (!el || !add_className) {return false;}
    if (el.classList){
      el.classList.add(add_className);
    } else {
      el.className += ' ' + add_className;
    }    
}
function elementRemoveClass(el, className) {
    var remove_className = className || false;
    if (!el || !remove_className) {return false;}
    if (el.classList){
      el.classList.remove(remove_className);
    } else {
      el.className = el.className.replace(new RegExp('(^|\\b)' + remove_className.split(' ').join('|') + '(\\b|$)', 'gi'), ' ');
    }
}
function elementHasClass(el, className) {
    if (el.classList){
        return el.classList.contains(className);
    } else {
        return new RegExp('(^| )' + className + '( |$)', 'gi').test(el.className);
    }
}