SimpleEventInterface

eve.js

var Eve = function() {
    this._events = {};
};
Eve.prototype = {
    constructor: Eve,
    on: function(evName, handler) {
        var events = this._events;

        if (!(evName in events)) {
            events[evName] = [];
        }
        events[evName].push(handler);
    },
    off: function(evName, handler) {
        var events = this._events;

        if (!(evName in events)) {
            return;
        }
        if (!handler) {
            events[evName] = [];
        }

        var handlerIdx = events[evName].indexOf(handler);
        if (handlerIdx >= 0) {
            events[evName].splice(handlerIdx, 1);
        }
    },
    trigger: function(evName, evData) {
        var events = this._events,
            handler;

        if (!(evName in events)) { return; }

        var i = 0, l = events[evName].length;
        for (; i < l; i++) {
            handler = events[evName][i];
            handler.handleEvent ? handler.handleEvent.call(this, evData)
                                : handler.call(this, evData);
        }
    }
};

test.js

// instance
var e = new Eve();

// handlers
var sayFoo = function(data) { console.log('foo!', data); };
var sayHoo = function(data) { console.log('hoo!', data); };
var sayWoo = { handleEvent: function(data) { console.log('woo!', data); } };

// listen
e.on('foo', sayHoo);
e.on('foo', sayFoo);
e.on('foo', sayWoo);

// call both two handlres
e.trigger('foo', 'bar');

// remove one
e.off('foo', sayFoo);

// call only one
e.trigger('foo', 'bar2');

// remove all
e.off('foo');

// no one called
e.trigger('foo', 'bar3');