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
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!'
})
})