Run through of setting up a basic node app with express
| var express = require('express'); | |
| // Middleware to parse body of HTTP requests | |
| var bodyParser = require('body-parser'); | |
| // Invokes function returned from require. | |
| // Creates an Express application; | |
| // express() returns Express object | |
| var app = express(); | |
| // Sets port equal to either the environment | |
| // PORT variable OR 3000 as default. | |
| // Can set up environment variables on servers | |
| // when deploying for production. | |
| var port = process.env.PORT || 3000; | |
| // Create parser for requests with | |
| // Content-Type: x-www-form-urlencoded | |
| var urlencodedParser = bodyParser.urlencoded({ extended: false }); | |
| // Create parser for requests with | |
| // Content-Type: application/json | |
| var jsonParser = bodyParser.json(); | |
| // Mounts specified middleware function(s) at specified path; | |
| // app.use() takes following params: | |
| // 1. path: string|RegExp | (string|RegExp)[] | |
| // 2. ...handlers: RequestHandler[] (callback functions, can be series of functions | |
| // separated by commas or array of functions) | |
| // Middleware function is executed when the base of | |
| // the requested path matches path param. | |
| // express.static() is built-in express middleware | |
| // to serve static files. | |
| // express.static() takes following params: | |
| // 1. root: string (dir from which static assets to be served) | |
| // 2. options?: serveStatic.ServeStaticOptions | |
| // Here we have a 'public' folder in root dir with a style.css file | |
| app.use('/assets', express.static(__dirname + '/public')); | |
| // Make your own middleware. | |
| app.use('/', function(req, res, next){ | |
| console.log('Request Url: ' + req.url); | |
| // Express provides next() for middleware to the | |
| // function that you give as callback when route is matched. | |
| // next() just means 'run the next middleware'; | |
| // Without next(), request will be left hanging. | |
| next(); | |
| }); | |
| // Executes this function if a GET request | |
| // is received to this url. | |
| app.get('/', function(req, res) { | |
| // Indicate body to be included in response. | |
| // Don't need to indicate Content-type header. | |
| // When browser sees href=assets/style.css it will | |
| // generate an HTTP req for site/assets/style.css, | |
| // and this will be handled by Node. | |
| // When it sees /assets it will handle request in | |
| // app.use('/assets' ...). | |
| res.send('<html><head><link href=assets/style.css type=text/css rel=stylesheet /></head><body><h1>Donuts</h1></body></html>'); | |
| }); | |
| // Use res.sendFile to serve an html file | |
| app.get('/form', function(req, res){ | |
| res.sendFile(__dirname + '/form.htm'); | |
| }); | |
| // :id indicates that id is a variable name. | |
| // Access id using req.params.id. | |
| // Can also access request query string using req.query.param, | |
| // where param is name from a query string name value pair | |
| // (ie url?param=4&name=value). | |
| // Now we can access urls such as: | |
| // /person/3 | |
| // /person/Jerry | |
| app.get('/person/:id', function(req, res) { | |
| res.send('<html><head></head><body><h1>Donuts for Person ' + req.params.id + '</h1></body></html>'); | |
| }); | |
| // Pass urlencodedParser (middleware we created earlier) | |
| // to post statement as a callback. | |
| // urlencodedParser is middleware that will be called | |
| // before function(req, res) is called. | |
| // urlencodedParser gives us access to req.body.param, | |
| // where param is name of name value pair in body of request. | |
| // So if '/person' is seen in the url, and it's of method post, | |
| // then this middleware and callback will be run. | |
| app.post('/person', urlencodedParser, function(req, res){ | |
| res.send('Thank you!'); | |
| console.log(req.body.firstname); | |
| console.log(req.body.lastname); | |
| }); | |
| // Pass jsonParser (middleware we created earlier) | |
| // to post statement as a callback. | |
| // jsonParser gives us access to req.body.param, | |
| // where param is name in json object in body of request. | |
| app.post('/personjson', jsonParser, function(req, res){ | |
| res.send('Thankyou for the json data'); | |
| console.log(req.body.firstname); | |
| console.log(req.body.lastname); | |
| }); | |
| // Send json data in response to GET from /api url | |
| app.get('/api', function(req, res) { | |
| res.json({ firstname: 'Jelly', lastname: 'Donut' }); | |
| }); | |
| // listen() calls http.createServer under the hood. | |
| // listen() takes the following params: | |
| // 1. port: number | |
| // 2. hostname: string | |
| // 3. backlog: number | |
| // 4. callback?: Function | |
| // returns a http.Server object. | |
| // Here we specify port 3000. | |
| app.listen(port); |
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