Author: Martins Zeltins Date: 2020-01-21

This application listens for every key press and tries to detect when an RFID tag has been scanned. When an RFID tag is scanned, there is less than 25 ms between each keystroke. So when we detect that between two keystrokes there has been a less than a 25 ms delay, we start adding them to our result string (keysPressed), otherwise, we clear it an start over again.

const ioHook = require('iohook')
const exec = require('child_process').exec

let currentTime = 0
let timeBetween = 0
let keysPressed = ''
let timesAdded = 0

let lastKeysPressed = [
	{ key: '', time: 0 },
	{ key: '', time: 0 }
]

function getKeyChar(rawcode)
{
	if (rawcode == 13) {
		return 'Enter'
	} else {
		return String.fromCharCode(rawcode)
	}
}

ioHook.on("keydown", event => {

	currentTime = Date.now()

	lastKeysPressed[0] = lastKeysPressed[1]

	lastKeysPressed[1] = {
		key: getKeyChar(event.rawcode),
		time: currentTime,
	}

	timeBetween = lastKeysPressed[1].time - lastKeysPressed[0].time

	if (timeBetween <= 25 && timesAdded === 0)
	{
		keysPressed += lastKeysPressed[0].key
		keysPressed += lastKeysPressed[1].key

		timesAdded++
	} else if (timeBetween <= 25 && timesAdded > 0) {
		keysPressed += lastKeysPressed[1].key

		if (keysPressed.includes('Enter')) {
			timesAdded = 0
		}
	} else {
		keysPressed = ''
		timesAdded = 0
	}

	if (keysPressed.includes('Enter')) {
		if (!isNaN(lastKeysPressed[0].key)) {
			exec('notepad')
		}
	}
	
	console.log(keysPressed)
})

ioHook.start()