A quick reference cheatsheet for Express, a flexible and streamlined web framework for Node.js.
"Create project, add package.json configuration $ mkdir myapp # create directory $ cd myapp # enter the directory $ npm init -y # Initialize a configuration Install dependencies $ npm install express Entry file index.js add code: const express = require('express') const app = express() const port = 3000 app.get('/', (req, res) => { res. send('Hello World!') }) app. listen(port, () => { console.log(`Listening port on ${port}`) }) Run the application using the following command $ node index.js
Usage: express [options] [dir]
Options:
-h, --help output usage information
--version output version number
-e, --ejs add ejs engine support
--hbs add hbs engine support
--pug add pug engine support
-H, --hogan add hogan.js engine support
--no-view No view engine generated
-v, --view <engine> add view <engine> support (ejs|hbs|hjs|jade|pug|twig|vash) (default jade)
-c, --css <engine> add stylesheet <engine> support (less|stylus|compass|sass) (default css)
--git add .gitignore
-f, --force force non-empty directories
Create a myapp project
$ express --view=pug myapp
# run the application
$ DEBUG=myapp:*npm start
express.json() — #
express.raw() — #
express.Router() — #
express.static() — #
express.text() — #
express.urlencoded() — #
router.all() — #
router.METHOD() — #
router.param() — #
router.route() — #
router.use() — #
var express = require('express')
var app = express()
console.dir(app.locals.title)
//=> 'My App'
console.dir(app.locals.email)
//=> '[email protected]'
app.locals — Local variables in the application #
app.mountpath — Path pattern for mounting sub-apps #
mount — The child application is mounted on the parent application, and the event is triggered on the child application #
app.all() — #
app.delete() — #
app.disable() — #
app.disabled() — #
app.enable() — #
app.enabled() — #
app.engine() — #
app.get(name) — #
app.get(path, callback) — #
app.listen() — #
app.METHOD() — #
app.param() — #
app.path() — #
app.post() — #
app.put() — #
app.render() — #
app.route() — #
app.set() — #
app.use() — #
req.app — #
req.baseUrl — #
req.body — #
req.cookies — #
req.fresh — #
req.hostname — #
req.ip — #
req.ips — #
req.method — #
req.originalUrl — #
req.params — #
req.path — #
req.protocol — #
req.query — #
req.route — #
req.secure — #
req.signedCookies — #
req.stale — #
req.subdomains — #
req.xhr — #
req.accepts() — #
req.acceptsCharsets() — #
req.acceptsEncodings() — #
req.acceptsLanguages() — #
req.get() — Get HTTP request header fields #
req.is() — #
req.param() — #
req.range() — #
app.get('/', function (req, res) {
console.dir(res.headersSent) //false
res.send('OK')
console.dir(res.headersSent) //true
})
res.app — #
res.headersSent — #
res.locals — #
res.append() — #
res.attachment() — #
res.cookie() — #
res.clearCookie() — #
res.download() — Prompt for files to download #
res.end() — end the response process #
res.format() — #
res.get() — #
res.json() — Send JSON response #
res.jsonp() — Send a response with JSONP support #
res.links() — #
res.location() — #
res.redirect() — Redirect request #
res.render() — render view template #
res.send() — Send various types of responses #
res.sendFile() — Send a file as an octet stream #
res.sendStatus() — #
res.set() — #
res.status() — #
res.type() — #
res.vary() — #
Called for any request passed to this router
router. use(function (req, res, next) {
//.. some logic here .. like any other middleware
next()
})
will handle any request ending in /events
//depends on where the router "use()"
router. get('/events', (req, res, next) => {
//..
})
The res object represents the HTTP response sent by the Express application when it receives an HTTP request
app.get('/user/:id', (req, res) => {
res.send('user' + req.params.id)
})
A req object represents an HTTP request and has properties for the request query string, parameters, body, HTTP headers, etc.
app.get('/user/:id', (req, res) => {
res.send('user' + req.params.id)
})
res. end()
res.status(404).end()
End the response process. This method actually comes from the Node core, specifically the response.end() method of http.ServerResponse
res.json(null)
res.json({ user: 'tobi' })
res.status(500).json({ error: 'message' })
app.all('/secret', function (req, res, next) {
console.log('access secret section...')
next() // Pass control to the next handler
})
app.delete('/', function (req, res) {
res.send('DELETE request to homepage')
})
app.disable('trust proxy')
app.get('trust proxy')
// => false
app.disabled('trust proxy')
// => true
app.enable('trust proxy')
app.disabled('trust proxy')
// => false
var engines = require('consolidate')
app.engine('haml', engines.haml)
app.engine('html', engines.hogan)
var express = require('express')
var app = express()
app.listen(3000)
const express = require('express')
const app = express()
//Respond to "hello world" when making a GET request to the homepage
app.get('/', (req, res) => {
res.send('hello world')
})
// GET method routing
app.get('/', (req, res) => {
res.send('GET request to the homepage')
})
// POST method routing
app.post('/', (req, res) => {
res.send('POST request to the homepage')
})
function logOriginalUrl (req, res, next) {
console.log('ReqURL:', req.originalUrl)
next()
}
function logMethod (req, res, next) {
console.log('Request Type:', req.method)
next()
}
const log = [logOriginalUrl, logMethod]
app.get('/user/:id', log,
(req, res, next)=>{
res.send('User Info')
}
)
app.set('view engine', 'pug')
Create a Pug template file named index.pug in the views directory with the following content
html
the head
title= title
the body
h1=message
Create a route to render the index.pug file. If the view engine property is not set, the extension of the view file must be specified
app.get('/', (req, res) => {
res. render('index', {
title: 'Hey', message: 'Hello there!'
})
})