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Express Cheat Sheet

A quick reference cheatsheet for Express, a flexible and streamlined web framework for Node.js

Programming
Config
Format

Example

Using templates

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!' }) })

Middleware

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') } )

Routing

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') })

app.listen([port[, host[, backlog]]][, callback])

var express = require('express') var app = express() app.listen(3000)

app.engine(ext, callback)

var engines = require('consolidate') app.engine('haml', engines.haml) app.engine('html', engines.hogan)

app.disabled(name)

app.disabled('trust proxy') // => true app.enable('trust proxy') app.disabled('trust proxy') // => false

app.disable(name)

app.disable('trust proxy') app.get('trust proxy') // => false

app.delete

app.delete('/', function (req, res) { res.send('DELETE request to homepage') })

app.all

app.all('/secret', function (req, res, next) { console.log('access secret section...') next() // Pass control to the next handler })

res.json([body])

res.json(null) res.json({ user: 'tobi' }) res.status(500).json({ error: 'message' })

res. end()

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

Getting Started

Response

app.get('/', function (req, res) { console.dir(res.headersSent) //false res.send('OK') console.dir(res.headersSent) //true })

#Attribute

:- :-
res.app #
res.headersSent #
res.locals #

#Method

:- :-
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() #

Request

#Attribute

:- :-
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 #

#Method

:- :-
req.accepts() #
req.acceptsCharsets() #
req.acceptsEncodings() #
req.acceptsLanguages() #
req.get() Get HTTP request header fields #
req.is() #
req.param() #
req.range() #

Application

var express = require('express') var app = express() console.dir(app.locals.title) //=> 'My App' console.dir(app.locals.email) //=> '[[email protected]](/cdn-cgi/l/email-protection)'

#Attribute

:- :-
app.locals Local variables in the application #
app.mountpath Path pattern for mounting sub-apps #

#Events

:- :-
mount The child application is mounted on the parent application, and the event is triggered on the child application #

#Method

:- :-
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() #

Router

:- :-
router.all() #
router.METHOD() #
router.param() #
router.route() #
router.use() #

express()

:- :-
express.json() #
express.raw() #
express.Router() #
express.static() #
express.text() #
express.urlencoded() #

express -h

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

Hello World

  • "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