How should I structure my application? There is no definitive answer to this question. The answer depends on the scale of your application and the team that is involved. To be as flexible as possible, Express makes no assumptions in terms of structure. Routes and other application-specific logic can live in as many files as you wish, in any directory structure you prefer. View the following examples for inspiration: Route listings Route map MVC style controllers Also, there are third-party ex

express.Router([options]) Creates a new router object. var router = express.Router([options]); The optional options parameter specifies the behavior of the router. Property Description Default Availability caseSensitive Enable case sensitivity. Disabled by default, treating “/Foo” and “/foo” as the same. mergeParams Preserve the req.params values from the parent router. If the parent and the child have conflicting param names, the child’s value take precedence. false 4.5.0+ strict Enable st

Use the application generator tool, express-generator, to quickly create an application skeleton. Install express-generator with the following command: $ npm install express-generator -g Display the command options with the -h option: $ express -h Usage: express [options] [dir] Options: -h, --help output usage information -V, --version output the version number -e, --ejs add ejs engine support (defaults to jade) --hbs add handlebars

Events

When running an Express app behind a proxy, set (by using app.set()) the application variable trust proxy to one of the values listed in the following table. Although the app will not fail to run if the application variable trust proxy is not set, it will incorrectly register the proxy’s IP address as the client IP address unless trust proxy is configured. Type Value Boolean If true, the client’s IP address is understood as the left-most entry in the X-Forwarded-* header. If false, the app i

Define error-handling middleware functions in the same way as other middleware functions, except error-handling functions have four arguments instead of three: (err, req, res, next). For example: app.use(function(err, req, res, next) { console.error(err.stack); res.status(500).send('Something broke!'); }); You define error-handling middleware last, after other app.use() and routes calls; for example: var bodyParser = require('body-parser'); var methodOverride = require('method-override');

Express uses the debug module internally to log information about route matches, middleware functions that are in use, application mode, and the flow of the request-response cycle. debug is like an augmented version of console.log, but unlike console.log, you don’t have to comment out debug logs in production code. Logging is turned off by default and can be conditionally turned on by using the DEBUG environment variable. To see all the internal logs used in Express, set the DEBUG environment

Use the app.engine(ext, callback) method to create your own template engine. ext refers to the file extension, and callback is the template engine function, which accepts the following items as parameters: the location of the file, the options object, and the callback function. The following code is an example of implementing a very simple template engine for rendering .ntl files. var fs = require('fs'); // this engine requires the fs module app.engine('ntl', function (filePath, options, callba

app.use([path,] function [, function...]) Mounts the specified middleware function or functions at the specified path. If path is not specified, it defaults to “/”. A route will match any path that follows its path immediately with a “/”. For example: app.use('/apple', ...) will match “/apple”, “/apple/images”, “/apple/images/news”, and so on. Note that req.originalUrl in a middleware function is a combination of req.baseUrl and req.path, as shown in the following example. app.use('/admin', f

Adding the capability to connect databases to Express apps is just a matter of loading an appropriate Node.js driver for the database in your app. This document briefly explains how to add and use some of the most popular Node.js modules for database systems in your Express app: Cassandra CouchDB LevelDB MySQL MongoDB Neo4j PostgreSQL Redis SQLite ElasticSearch These database drivers are among many that are available. For other options, search on the npm site. Cassandra Module: cassandra-dr