express

1const express = require('express');
2const cors = require('cors')//cors for own server connected with own
3const app = express();
4require("dotenv").config();//dotenv config
5const port = process.env.PORT || 5000;
6
7//Middleware
8app.use(cors());
9app.use(express.json());
10
11app.get('/',(req,res) =>{
12    res.send('Server is ok')
13});
14
15app.listen(port, () =>{
16    console.log('Port is Ok');
17})

1const express = require('express')
2const cors = require('cors')
3const bodyParser = require('body-parser')
4require('dotenv').config()
5const ObjectId = require("mongodb").ObjectId;
6
7const app = express()
8app.use(cors())
9app.use(express.json())
10const port = process.env.PORT || 5000;
11
12app.get('/', (req, res)=>{
13    res.send('welcome to backend')
14})
15
16app.listen(port, () => {
17    console.log(`App listening at localhost:${port}`);
18})

1Express.js, or simply Express, is a web application framework for Node.js,
2released as free and open-source software under the MIT License.
3
4It is designed for building web applications and APIs.
5It has been called the de facto standard server framework for Node.js.

1# You can run the application generator with the npx command (available in Node.js 8.2.0).
2npx express-generator
3# For earlier Node versions, install the application generator as a global npm package and then launch it:
4npm install -g express-generator
5# For example, the following creates an Express app named myapp. The app will be created in a folder named myapp in the current working directory and the view engine will be set to Pug:
6express --view=pug myapp
7
8   create : myapp
9   create : myapp/package.json
10   create : myapp/app.js
11   create : myapp/public
12   create : myapp/public/javascripts
13   create : myapp/public/images
14   create : myapp/routes
15   create : myapp/routes/index.js
16   create : myapp/routes/users.js
17   create : myapp/public/stylesheets
18   create : myapp/public/stylesheets/style.css
19   create : myapp/views
20   create : myapp/views/index.pug
21   create : myapp/views/layout.pug
22   create : myapp/views/error.pug
23   create : myapp/bin
24   create : myapp/bin/www
25# Then install dependencies:
26cd myapp
27npm install
28# On MacOS or Linux, run the app with this command:
29DEBUG=myapp:* npm start
30# On Windows Command Prompt, use this command:
31set DEBUG=myapp:* & npm start
32# On Windows PowerShell, use this command:
33$env:DEBUG='myapp:*'; npm start

1npm install express
2npm install express --save
3Docs : https://expressjs.com/
4- Example API : https://jareer.xyz/ - 

1const http = require('http');
2const app = require('./app');
3
4const normalizePort = val => {
5  const port = parseInt(val, 10);
6
7  if (isNaN(port)) {
8    return val;
9  }
10  if (port >= 0) {
11    return port;
12  }
13  return false;
14};
15const port = normalizePort(process.env.PORT || '3000');
16app.set('port', port);
17
18const errorHandler = error => {
19  if (error.syscall !== 'listen') {
20    throw error;
21  }
22  const address = server.address();
23  const bind = typeof address === 'string' ? 'pipe ' + address : 'port: ' + port;
24  switch (error.code) {
25    case 'EACCES':
26      console.error(bind + ' requires elevated privileges.');
27      process.exit(1);
28      break;
29    case 'EADDRINUSE':
30      console.error(bind + ' is already in use.');
31      process.exit(1);
32      break;
33    default:
34      throw error;
35  }
36};
37
38const server = http.createServer(app);
39
40server.on('error', errorHandler);
41server.on('listening', () => {
42  const address = server.address();
43  const bind = typeof address === 'string' ? 'pipe ' + address : 'port ' + port;
44  console.log('Listening on ' + bind);
45});
46
47server.listen(port);
48
49