Simple Mediator

mediator.js

var mediator = {
    siblings: [],
    
    notify: function () {
        var args = Array.prototype.slice.call(arguments);
        
        this.siblings.forEach(function (sibling) {
            sibling.onNotify.apply(sibling, args);
        });
    },
    
    add: function (sibling) {
        if (this.siblings.indexOf(sibling) === -1 && typeof sibling.onNotify === 'function') {
            this.siblings.push(sibling);
        }
    },
    
    remove: function (sibling) {
        var index = this.siblings.indexOf(sibling);
        if (index > -1) {
            this.sibling.splice(index, 1);
        }
    }
};

Sibling.js

function Sibling() {
    mediator.add(this);
    this.id = Sibling.getUniqueID();
}

Sibling.getUniqueID = (function () {
    var id = 0;
    
    return function () {
        return id++;
    };
}());

Sibling.prototype.onNotify = function () {
    console.log(this.id);
};