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copied!<p>JavaScript uses lexical scoping - meaning, if you did this it would work:</p> <pre><code>var mongoClient = new MongoClient(new Server('localhost', 27017)); mongoClient.open(function(err, mongoClient) { var db1 = mongoClient.db("dev-db") , products = db1.collection('products'); app.get('/', function closedOverIndexRoute(req, res, next) { console.log(products); // this will work }); app.get('/users', user.list); // however, user.list will not be able to see `products` }); </code></pre> <p>A function doesn't become a closure (doesn't retain the values of its enclosing function) unless it's lexically (written) inside of the closure.</p> <p>However, you probably don't want to write your whole app as one big closure. Instead, you can use exports and require to get access to your products collection. For example, in a file called mongoconnect.js:</p> <pre><code>var mongoClient = new MongoClient(new Server('localhost', 27017)); var products; mongoClient.open(function(err, mongoClient) { var db1 = mongoClient.db("dev-db"); products = db1.collection('products'); }); module.exports = { getProducts: function() { return products; } }; </code></pre> <p>Then in your index.js file:</p> <pre><code>var products = require('mongoconnect').getProducts(); </code></pre> <p><strong>Another option (if you want to keep just app and index) is to use a pair of closures:</strong></p> <p>index.js:</p> <pre><code>module.exports = function(products) { return function index(req, res, next) { console.log(products); // will have closed-over scope now }; }; </code></pre> <p>app.js, inside of <code>mongoClient.open()</code>, where <code>products</code> is defined:</p> <pre><code>var index = require('./index')(products); </code></pre>

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