js hasClass, addClass, removeClass

function hasClass(el, className) {
    return el.classList ? el.classList.contains(className) : new RegExp('\\b'+ className+'\\b').test(el.className);
}
function addClass(el, className) {
    if (el.classList) el.classList.add(className);
    else if (!hasClass(el, className)) el.className += ' ' + className;
}
function removeClass(el, className) {
    if (el.classList) el.classList.remove(className);
    else el.className = el.className.replace(new RegExp('\\b'+ className+'\\b', 'g'), '');
}

//!hasClass(el, class)
//addClass(el, class);
//removeClass(el, class);