index.js

const HID = require('node-hid').HID;
const devices = require('node-hid').devices();
const EventEmitter = require('events');
const hidMap = require('./hidmap');

class UsbScanner extends EventEmitter {

	constructor(options) {
		options = options || {};

		let { 
			vendorID = undefined,
			productID = undefined,
			path = undefined, 
			vCardString = true,
			vCardSeperator = '|'
		} = options;

		super();

		this.vendorID = vendorID;
		this.productID = productID;
		this.path = path;
		this._vCardString = vCardString;
		this._vCardSeperator = vCardSeperator;

		this._hidMap = hidMap.standard;
		this._hidMapShift = hidMap.shift;

		// Bind 'this' to the methods
		this.startScanning = this.startScanning.bind(this);
	}

	static showDevices() {
		return devices;
	}


	startScanning() {
		try {
			if(this.path) this.hid = new HID(path);
			else if (this.vendorID && this.productID) this.hid = new HID(this.vendorID, this.productID);
			else throw 'Device cannot be found, please supply a path or VID & PID';
		} catch(error) {
			this.emit('error', error);
		}
		
		let scanResult = [];
		let vCard = [];

		this.hid.on('data', (data) => {
			const modifierValue = data[0];
			const characterValue = data[2];

			if (characterValue !== 0) {
				if (modifierValue === 2 || modifierValue === 20) {
					scanResult.push(this._hidMapShift[characterValue]);
				} else if (characterValue !== 40) {
					scanResult.push(this._hidMap[characterValue]);
				} else if (characterValue === 40) {
					let barcode = scanResult.join('');
					scanResult = [];

					barcode = removeUTF8(barcode);
					
					if (this._vCardString) {
						if (barcode === 'BEGIN:VCARD') {
							vCard.push(barcode);
						} else if (barcode === 'END:VCARD') {
							vCard.push(barcode);
							vCard = vCard.join(this._vCardSeperator);
							this.emit('data', vCard);
							vCard = [];
						} else if (vCard.length > 0 ) {
							vCard.push(barcode);
						} else this.emit('data', barcode);
					} else {
						this.emit('data', barcode);
					}
				}
			}
		});
		
	}

	stopScanning() {
		this.hid.removeAllListeners('data');
		this.hid.close();
	}

}


function removeUTF8(barcode) {
	let utf8 = barcode.slice(0, 7);
	if (utf8 === '\\000026') {
		barcode = barcode.slice(7);
		return barcode;
	} else return barcode;
}

module.exports = UsbScanner;