working-but-complicated.js

// In this example we'd like to have a factory that works per request and allows to keep track of created Models
// We create a factory per request and pass it around to the parts of the code that need access
// This can quickly lead to hard to messy code 

// factory.js
// 
// Basically a factory for factories
// For every request we create a new one

var Model = require('backbone').Model;

module.exports = function createFactory () {
    var allModels = [];

    return {
        createModel: function (data) {
            var model = new Model(data);
            allModels.push(model);
            return model;
        },
        serializeModels: function () {
            return allModels.map(function (model) {
                return model.toJSON();
            });
        },
        reset: function () {
            allModels = [];
        }
    }
};

// view.js
var Factory = require('./factory');
var View = require('backbone').View;

module.exports = View.extend({
    initialize: function (args) {
        this.viewState = args.factory.createModel({
            collapsed: true,
            hidden: false
        });
    }
});

// app.js
var express = require('express'),
    app = express(),
    factory = require('./factory'),
    View = require('./view');

app.all('*', function(req, res, next) {
    // We create a factory for every request and pass it to the view
    // This quickly becomes hard to manage if you need it in multiple parts of the code,
    // It would be much better if every part of the application that needs access
    // could simply import the singleton using the standard `require` or get it from some kind
    // of global scope that is created per request and doesn't get polluted when things are done async
    
    var perRequestFactory = factory();
    var view = new View({
        factory: perRequestFactory
    });

    var responseTime = Math.random() * 2500; // random response time
    // Simulate async tasks
    setTimeout(function () {
        res.send(perRequestFactory.serializeModels());
    }, responseTime);

});

app.listen(8000);