Implementing events in custom object

The addEventListener function is a method of Element class. One way is to make CustomObject inherit from Element like this:

CustomObject.prototype = Element.prototype;

The problem is that Element class may have different implementations among different browsers. So for example firing events may not be easy (see this post).

So I advice doing this by yourself. It is not difficult, try something like this:

var CustomObject = function () {
    var _this = this;
    _this.events = {};

    _this.addEventListener = function(name, handler) {
        if (_this.events.hasOwnProperty(name))
            _this.events[name].push(handler);
        else
            _this.events[name] = [handler];
    };

    _this.removeEventListener = function(name, handler) {
        /* This is a bit tricky, because how would you identify functions?
           This simple solution should work if you pass THE SAME handler. */
        if (!_this.events.hasOwnProperty(name))
            return;

        var index = _this.events[name].indexOf(handler);
        if (index != -1)
            _this.events[name].splice(index, 1);
    };

    _this.fireEvent = function(name, args) {
        if (!_this.events.hasOwnProperty(name))
            return;

        if (!args || !args.length)
            args = [];

        var evs = _this.events[name], l = evs.length;
        for (var i = 0; i < l; i++) {
            evs[i].apply(null, args);
        }
    };
}

Now using it is as simple as:

var co = new CustomObject();
co.addEventListener('textChange', function(name) {
    console.log(name); 
});
co.fireEvent('textChange', ['test']);

This is a basic solution. You may want to alter it, but I think you should grasp the idea.