Node Playground used while learning Node.js

node_playground.js

// I created this script as a playground when learning node.js
// The Majority of examples are grabbed from https://nodejs.dev/

/**
 * Make this server reacheable by the world.
 * Install ngrok and type `ngrok PORT` and the PORT you want is exposed to the 
 * internet. You will get a ngrok.io domain, but with a paid subscription you 
 * can get a custom URL as well as more security options.
 * 
 * Another service you can use is https://github.com/localtunnel/localtunnel
 */
const http = require('http');
const hostname = '127.0.0.1';
const port = 3000; /* ¿process.env.PORT? */
const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World!');
});
server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});


// process does not require a "require", it's automatically available.
// I get 'undefined' when I run just `node app.js`
// I have to manually send the value using `NODE_ENV=debug node app.js` or
// it will probably work if its exported as an environment variable.
console.log(`NODE_END: ${process.env.NODE_ENV}`)


// SIGTERM is the signal that tells a process to gracefully terminate. 
// It is the signal that's sent from process managers like upstart or 
// supervisord and many others.
// It can be invoked by calling `process.kill(process.pid, 'SIGTERM')`
process.on('SIGTERM', () => {
  server.close(() => {
    console.log('Process terminated')
  })
})


// Print how many oranges and apples are printed
const oranges = ['orange', 'orange']
const apples = ['just one apple']
oranges.forEach(fruit => {
  console.count(fruit)
})
apples.forEach(fruit => {
  console.count(fruit)
})


// Print the call stack trace
const function2 = () => console.trace()
const function1 = () => function2()
function1()


// Calculate how much time a function takes to run, using time() and timeEnd()
const doSomething = () => console.log('test')
const measureDoingSomething = () => {
  console.time('doSomething()')
  //do something, and measure the time it takes
  doSomething()
  console.timeEnd('doSomething()')
}
measureDoingSomething()


// Print to the error log (or console)
console.error('hmm')


// Prints hi! in yellow
// low level way: console.log('\x1b[33m%s\x1b[0m', 'hi!')
// Instead using an easy to use library called chalk
// $ npm install chalk
const chalk = require('chalk')
console.log(chalk.yellow('hi!'))


// Create a 10-step progress bar and every 100ms one step is
// completed. When the bar completes it clears the interval
// Install a package called progress
// $ npm install progress
const ProgressBar = require('progress')
const bar = new ProgressBar(':bar', { total: 10 })
const timer = setInterval(() => {
  bar.tick()
  if (bar.complete) {
    clearInterval(timer)
  }
}, 100)


// Accept input, process and print out the result in this case a greeting
const readline = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
})
readline.question(`What's your name?`, name => {
  console.log(`Hi ${name}!`)
  readline.close()
})