expressjs routing code example

Example 1: express hello world

//to run : node filename.js
const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => res.send('Hello World!'))

app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`))

//visit localhost:3000
// assuming you have done 1) npm init 2) npm install express

Example 2: express router file

var express = require('express');
var router = express.Router();

// middleware that is specific to this router
router.use(function timeLog (req, res, next) {
  console.log('Time: ', Date.now());
  next();
});
// define the home page route
router.get('/', function (req, res) {
  res.send('Birds home page');
});
// define the about route
router.get('/about', function (req, res) {
  res.send('About birds');
});

module.exports = router;

Example 3: express route parameters

app.get('/users/:userId/books/:bookId', function (req, res) {
  res.send(req.params)
})

Example 4: nodejs express routing get

const express = require('express');
const mysql = require('mysql');

// Connecting with database
const db = mysql.createConnection({
  host: 'localhost',					// The host you're using
  user: 'yourusername',					// The username you use to enter database
  password: 'yourpassword'				// Your password to your username
});

db.connect((error) => {
  if(error) {
    throw error;
  }
  console.log('MySQL Connected');
});

const app = express();

app.get('yourroute', (request, response) => {
  let sql = 'SELECT * FROM yourtable';
  let query = db.query(sql, (error, result) => {
    if(error) {
      throw error;
    }
    console.log(result)					// Use the result you get back here
  })
});

app.listen('3000', () => {
  console.log('Server is listening on port 3000');
});

Example 5: nodejs express routing

// You need to install the following packages
npm install --save mysql express
// And if you don't want to restart your server after every little change
npm install -g nodemon

Example 6: express() vs express.router()

var express = require('express');

var router = express.Router();

router.get('/', function(req, res) {
    res.send('GET handler for /dogs route.');
});

router.post('/', function(req, res) {
    res.send('POST handler for /dogs route.');
});

module.exports = router;