Node Debugger demo

debuggerdemo.js

/*
 Simple demo to show how the node inspector works

  ✨ 1: Run with:
  node --inspect-brk debuggerdemo.js

  By default, the debug process runs on "ws://127.0.0.1:9229", but you can change the port. See node --help for more info

    --inspect[=[host:]port]                         activate inspector on host:port (default: 127.0.0.1:9229)
    --inspect-brk[=[host:]port]                     activate inspector on host:port and break at start of user script
    --debug-port, --inspect-port=[host:]port        set host:port for inspector

  ✨ 2: Goto Chrome and open
  chrome://inspect/#devices

  Protip for mac users (or use https://github.com/sindresorhus/open-cli)
  open -a 'Google Chrome' 'chrome://inspect/#devices' &; node --inspect-brk debuggerdemo.js

  ✨ 3: Click "Open dedicated DevTools for Node"

  ✨ 4: If your connection list is empty (or doesn't show 127.0.0.1:9229, please add it to the list by via "Add connection")

  ✨ 5: When DevTools fires up - check "Pause on uncaught exceptions" (we will need it to autopause later when global.foo.bar.baz() is executed)

  ✨ 6: Profit!

  More reading:
    https://nodejs.org/en/docs/guides/debugging-getting-started
    https://nodejs.org/api/debugger.html
    https://code.visualstudio.com/docs/nodejs/nodejs-debugging

    https://github.com/debug-js/debug
    https://github.com/pinojs/pino

    https://medium.com/@paul_irish/debugging-node-js-nightlies-with-chrome-devtools-7c4a1b95ae27
*/
const {log} = console

function someLogic(x) {
  return x + 1000
}

function someLoop() {
  // Test loop 2
  for (let j=0; j<10; j++) {
    const someValue = someLogic(j)
  }
}

log('Debug mode?', require('inspector').url())

const a = 1 + 2
const b = 3 + 5

log(b / 0) // <----------- Will not crash. Infinity is not considered an exception
log(a, b)

// Poor mans feature: the hardcoded debugger keyword (please don't leave this in production :)
debugger // <----------- The program will automatically stop here (if inspector is enabled)

// Test loop 1
for (let i=0; i<5; i++) {
  log(i)

  // Poor mans conditional breakpoint
  if (i == 3) {
    log('I have stopped')
    debugger
  }
}

// Simulating unknown logic without any logging
someLoop()
// What just happened here? And no logging. Oh noez. What to do?

// Protip: 
// Let's use the fact that console.log returns undefined and 
// put a conditional breakpoint in the inspector with `console.log(someValue)`
debugger

// Simulating unknown logic with conditional breakpoint logging
someLoop()

global.foo.bar.baz() // <----------- The program will crash here (if "Pause on uncaught exceptions" is toggled)

log('I will fail to be logged')

debuggerdemo.mp4

debuggerdemo.mp4