postMessage pubsub

app.service('appPubSub', function($window) {

    this.subscribe = function(subject, cb) {
        $window.addEventListener('message', function(event) {
            if (typeof(event.data.message) === 'string') {
                event.data.message = JSON.parse(event.data.message.replace(/\&dquot/g, '"').replace(/\&squot/g, "'"));
            }
            return event.data.subject === subject && cb(event.data.message); 
        });
    };

    this.publish = function(subject, msg) {
        var msgStr = JSON.stringify(msg).replace(/[']/g, '&squot').replace(/["]/g, '&dquot');
        $window.postMessage({ subject: subject, message: msgStr });
    };
});