notify.js #1

Mjs.Notifier = function () {
    this.handlers = {};
};
Mjs.Notifier.prototype = {
    publish: function (message_name, data) {
        if (message_name == null || !message_name.length){
            console.log("Notifier.publish: message_name is null");
        } else if (this.handlers[message_name]) {
            var numHandlers =this.handlers[message_name].length, i;
            for (i = 0; i < numHandlers; ++i){
               this.handlers[message_name][i](message_name, data);
            }
        }
    },
    subscribe: function (message_name, handler) {
        if (message_name == null || !message_name.length ) {
            console.log("Notifier.subscribe: message_name is null");
        } else {
            (this.handlers[message_name] || (this.handlers[message_name] = []));
           this.handlers[message_name].push(handler);
        }
    },
    unsubscribe: function (message_name, handler) {
        if (message_name == null || !message_name.length) {
            console.log("Notifier.unsubscribe: message_name is null");
        } else if (this.handlers[message_name]) {
            var handlerIndex = -1, i = 0;
            var numHandlers = this.handlers[message_name].length;
            for (i = 0; i < numHandlers; ++i) {
                if (this.handlers[message_name][i] == handler) {
                    handlerIndex = i;
                    break;
                }
            }
            if (handlerIndex != - 1) {
               this.handlers[message_name].splice(handlerIndex, 1);
            } else {
                console.log("couldn't unsubscribe from " + message_name);
            }
        }
    }
};
Mjs.notify = new Mjs.Notifier();