express4.md

Express 4

Installation

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

Basics

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

const 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

$ npm i -S <package_name>

• 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
• connect-cors: CORS
• connect-redis