Express JS

basic-auth.js

const express = require('express')
const basicAuth = require('express-basic-auth')
const app = express()

app.use('/secret', basicAuth({
    users: { 'sounds': 'supersecret' },
    unauthorizedResponse: (req) => {
      return req.auth ? ('Credentials rejected') : 'No credentials provided'
    },
    challenge: true,
    realm: 'Imb4T3st4pp'
}))

app.get('/secret', (req, res) => res.send('The secret is revealed'))

app.listen(8080, () => console.log('Example app listening on port 8080!'))

error-handling.js

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

function throwError(request, response, next) {
  throw new Error('Error thrown');
}

function nextWithError(request, response, next) {
  next(new Error('Next with Error'));
}

function asynchError(request, response, next) {
  new Promise((resolve, reject) => {
    setTimeout(function () {
      reject('Asynch Error');
    }, 2000);
  }).catch(error => {
    next(new Error(error));
  });
}

function uncatchedError(request, response, next) {
  undefined.catch(error => {
    next(new Error(error));
  });
}

function notFound(request, response) {
  response.status(404).json({
    page: 'Not Found'
  });
}

function errorHandler (error, request, response, next) {
  if (response.headersSent) {
    return next(err);
  }
  response.status(500).json({
    page: 'Error handler',
    error: error.message
  });
}

app.get('/throwError', throwError);

app.get('/nextWithError', nextWithError);

app.get('/asynchError', asynchError);

app.get('/uncatchedError', uncatchedError);

app.get('*', notFound);

app.use(errorHandler);

const port = 8080;

app.listen(port, error => {
  if (error) {
    return console.log(error.message);
  }
  console.log(`Process started listening on port ${port}`);
});

etag.js

const express = require('express');

const app = express();
const port = 8080;
let counter = 0;

app.set('etag', 'strong');
app.set('query parser', 'extended');
app.disable('x-powered-by');

app.get('/', (req, res) => {
  counter += 1;
  let body = `Counter: ${counter}`;
  res.status(200);
  res.send(body);
});

app.listen(port, () => console.log(`Example app listening on port ${port}!`));