express.js documentation 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 js server
const express = require('express');
const app = express();
const PORT = process.env.PORT || 3000;
app.get('/', (req, res) => {
res.send('<h1>Some HTML</h1>');
res.send('<p>Even more HTML</p>');
});
app.listen(PORT, () => console.log(`Server is listening on port ${PORT}`));
Example 3: node js express
basic server
const express =require('express');
const app = express();
const PORT = 5000;
app.get('/',(req,res)=>{
res.json({message: 'Welcome to the backend'})
})
app.listen(PORT ,()=>console.log(`Connected to ${PORT}`)
Example 4: express redirect
res.redirect('/foo/bar')
res.redirect('http://example.com')
res.redirect(301, 'http://example.com')
res.redirect('../login')
Example 5: node js express
// node js -> express -> basic example: static folder, 404 page
const express = require('express');
const path = require('path');
const PORT = process.env.PORT || 5000;
const app = express();
function error404(req, res) {
res.status(404);
if (req.accepts('html')) {
res.sendFile(path.join(__dirname, 'public/errors/404.html'));
return;
}
if (req.accepts('json')) {
res.send({
status: 404,
error: 'Not found'
});
return;
}
res.type('txt').send('404 - Not found');
}
app
.use(express.static(path.join(__dirname, 'public')))
.use(error404)
.listen(PORT, () => console.log(`Listening on ${ PORT }`));
Example 6: require express server.js
const express = require('express')const app = express() app.get('/', function (req, res) { res.send('Hello World')}) app.listen(3000)