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: express route parameters
Route path: /users/:userId/books/:bookId
Request URL: http://localhost:3000/users/34/books/8989
req.params: { "userId": "34", "bookId": "8989" }
Example 6: widlicard in express router
//This route path will match acd and abcd.
app.get('/ab?cd', function (req, res) {
res.send('ab?cd')
})
//This route path will match abcd, abbcd, abbbcd, and so on.
app.get('/ab+cd', function (req, res) {
res.send('ab+cd')
})
//This route path will match abcd, abxcd, abRANDOMcd, ab123cd, and so on.
app.get('/ab*cd', function (req, res) {
res.send('ab*cd')
})
//This route path will match /abe and /abcde.
app.get('/ab(cd)?e', function (req, res) {
res.send('ab(cd)?e')
})
//This route path will match anything with an “a” in it.
app.get(/a/, function (req, res) {
res.send('/a/')
})
//This route path will match butterfly and dragonfly,
//but not butterflyman, dragonflyman, and so on.
app.get(/.*fly$/, function (req, res) {
res.send('/.*fly$/')
})