Event delegation using JavaScript

var sb = (function () {
    var eventObject = {};
    document.body.addEventListener('click', function(e){
        var el = e.target;
        var parent = el.parentElement;
        while(parent !== document.body){
            for(var item in eventObject){
                var elements = document.querySelectorAll(item);
                for(var i = 0, ilen = elements.length; i < ilen; i++){
                    if(el === elements[i]){
                        eventObject[item].call(el, e);
                        return;
                    }
                }
            }
            el = parent;
            parent = el.parentElement;
        }
    }, false);
    
    return {
        on: function(event, selector, callback){
            eventObject[selector] = callback;
            return sb;
        }
    }
})();