Express.js 4 Cheatsheet

Installation

• $ sudo npm install express: install the latest Express.js locally

• $ sudo npm install express@4.2.0 --save: install Express.js v4.2.0 locally and save to package.json

• $ sudo npm install -g express-generator@4.0.0: install Express.js command-line generator v4.0.0

Generator

Usage: $ express [options] [dir]

Options:

• -h: print the usage information

• -V: print the express-generator version number

• -e: add ejs engine support, defaults to jade if omitted

• -H: add hogan.js engine support

• -c <library> add CSS support for (less|stylus|compass), defaults to plain CSS if omitted

• -f: generate into a non-empty directory

Basics

• var express = require('express'): include the module

• var app = express(): create an instance

• app.listen(portNumber, callback): start the Express.js server

• http.createServer(app).listen(portNumber, callback): start the Express.js server

• app.set(key, value): set a property value by the key

• app.get(key): get a property value by the key

HTTP Verbs and Routes

• app.get(urlPattern, requestHandler[, requestHandler2, ...])

• app.post(urlPattern, requestHandler[, requestHandler2, ...])

• app.put(urlPattern, requestHandler[, requestHandler2, ...])

• app.delete(urlPattern, requestHandler[, requestHandler2, ...])

• app.all(urlPattern, requestHandler[, requestHandler2, ...])

• app.param([name,] callback):

• app.use([urlPattern,] requestHandler[, requestHandler2, ...])

Request

• request.params: parameters middlware

• request.param: extract one parameter

• request.query: extract query string parameter

• request.route: return route string

• request.cookies: cookies, requires cookie-parser

• request.signedCookies: signed cookies, requires cookie-parser

• request.body: payload, requires body-parser

Request Header Shortcuts

• request.get(headerKey): value for the header key

• request.accepts(type): checks if the type is accepted

• request.acceptsLanguage(language): checks language

• request.acceptsCharset(charset): checks charset

• request.is(type): checks the type

• request.ip: IP address

• request.ips: IP addresses (with trust-proxy on)

• request.path: URL path

• request.host: host without port number

• request.fresh: checks freshness

• request.stale: checks staleness

• request.xhr: true for AJAX-y requests

• request.protocol: returns HTTP protocol

• request.secure: checks if protocol is https

• request.subdomains: array of subdomains

• request.originalUrl: original URL

Response

• response.redirect(status, url): redirect request

• response.send(status, data): send response

• response.json(status, data): send JSON and force proper headers

• response.sendfile(path, options, callback): send a file

• response.render(templateName, locals, callback): render a template

• response.locals: pass data to template

Handlers Signatures

• function(request, response, next) {}: request handler signature

• function(error, request, response, next) {}: error handler signature

Stylus and Jade

app.set('views', path.join(__dirname, 'views'))
app.set('view engine', 'jade')

app.use(require('stylus').middleware(path.join(__dirname, 'public')))

Body

var bodyParser = require('body-parser')
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({
    extended: true
}))

Static

app.use(express.static(path.join(__dirname, 'public')))

Connect Middleware

$ sudo npm install <package_name> --save

• body-parser request payload

• compression gzip

• connect-timeout

• cookie-parser Cookies

• cookie-session Session via Cookies store

• csurf CSRF

• errorhandler error handler

• express-session session via in-memory or other store

• method-override HTTP method override

• morgan server logs

• response-time

• serve-favicon favicon

• serve-index

• serve-static static content

• vhost

Other Popular Middleware

• cookies and keygrip: analogous to cookie-parser

• raw-body

• connect-multiparty, connect-busboy

• qs: analogous to query

• st, connect-static analogous to staticCache

• express-validator: validation

• less: LESS CSS

• passport: authentication library

• helmet: security headers

• cors: CORS

• connect-redis