How to Check If User Input Is from Barcode Scanner or Keyboard

How to Check if User input is from Barcode Scanner or Keyboard?

You could monitor the time it took for the code to be entered. A reader would enter the code much faster than a human typing it in.

How do I distinguish between a scanner input and keyboard input in Javascript?

It is not necessary to judge from keyboard/barcode scanner.

If you decide the Enter(Carriage Return) key notification as input completion on any device, you can use it as simplest trigger to execute Price Look Up/input value verification.

Most scanners can add suffix code to the scanned barcode data for notification.

The most commonly used is the Enter key, but the Tab key may also be used.

By sending the suffix code by the barcode scanner, the possibility that the scanner notification and the key input are mixed is much lower than the timeout detection.

You can do as follows.

Using the setting barcode, it is set to inform that keys such as Enter, Tab etc. which are not normally included in the barcode as a suffix.
Bind an event listener for the corresponding suffix key to the text input field.
The key code is judged in the event listener, and if it is the suffix key, it assumes that the input of the barcode data is complete, carries out processing such as Price Look Up/input value verification, and moves the input focus to the next field.

For example see this article.

execute function on enter key

In Addition:

Your worries seem to be overwhelmed by situations that do not occur often.

If it really happens to be a problem, you should give up dealing with JavaScript.

Please acquire scanner data with another program by the following method. Please notify it to the application in some way.

If you want to continue keyboard input emulation, it is better to capture data before the browser or application is notified.

SetWindowsHookExW function / LowLevelKeyboardProc callback function

EasyHook / Indieteur/GlobalHooks

hook into linux key event handling / uinput-mapper

The Linux keyboard driver / LKL Linux KeyLogger / kristian/system-hook

system wide keyboard hook on X under linux / Error when trying to build a Global Keyboard Hook in Ubuntu Linux / 10.5.2 Keyboard and Pointer Events

Alternatively, set the scanner to serial port mode and have a dedicated program to receive it.

Serial API

JavaScript/JQuery communicate with SerialPort/COM1

Questions tagged opos / Questions tagged pos-for-.net / Questions tagged javapos

How do I tell if keyboard input is coming from a barcode scanner?

You'll get input from both. Not simultaneously, of course. It will all be placed into a queue, but Windows will process key events from both keyboards.

Don't be helpless, though. As David Heffernan suggests, you can easily figure this out yourself by plugging in both keyboards to your computer, opening up Notepad, and typing random characters to see which one generates input.

You reply that you want to "check that with C# code", but I have no idea what that means. How about creating a console app that reads input from the keyboard and displays it on the screen?

using System;

class AdvancedKeyboardTester
{
   static void Main(string[] args)
   {
      for (; ;)
      {
         Console.ReadKey();
      }
   }
}

Press Ctrl+C when you tire of the fun and want to quit the program.

Edit: It sounds like you're looking for the RegisterRawInputDevices function, which allows you to enable raw input for all of your keyboards, and then enumerate through the results to determine which device sent the message.

Fortunately, it looks like someone has already written a C# wrapper library for this, available for download on Code Project: Using Raw Input from C# to handle multiple keyboards

Edit 2: (it seems the information just keeps tricking in from the comments)

If you're using a barcode scanner, this gets a lot easier. Because they're explicitly designed for this purpose, they're almost all programmable. Meaning that you can tell them to prefix (and/or suffix) their input with some sentinel characters that indicate the input is coming from the barcode scanner, rather than a standard keyboard. (Check your barcode scanner's user manual for more information.) Then, all you have to do is filter out the keyboard input based on the presence or absence of those sentinel characters. You can also check for how quickly the characters between the prefix and suffix were entered.

Detect when input box filled by keyboard and when by barcode scanner.

Well a barcode won't fire any key events so you could do something like:

$('#my_field').on({
    keypress: function() { typed_into = true; },
    change: function() {
        if (typed_into) {
            alert('type');
            typed_into = false; //reset type listener
        } else {
            alert('not type');
        }
    }
});

Depending on when you want to evaluate this, you may want to do this check not on change but on submit, or whatever.

Allow Only Barcode Scanner and Eliminate Keyboard Input

The basic idea is to check:

if KeyUp and KeyDown events are fired of same keys and within specified time (say 17milliseconds), as this can be only done using Barcode scanner.

No one can trigger KeyDown and KeyUp event of same key within 17 milliseconds. For example it will take more than specified time for someone to Press and Release same key, however he can hit punch to keyboard that will push multiple keys all together and trigger their KeyDown and KeyUp events, but all no keys will have KeyUp and KeyDown events fired synchronously. So by this way you can detect whether input made by regular keyboard or barcode scanner.

Please have a look below:

public partial class BarcodeReader : Form
    {

        char cforKeyDown = '\0';
        int _lastKeystroke = DateTime.Now.Millisecond;
        List<char> _barcode = new List<char>(1);
        bool UseKeyboard = false;
        public BarcodeReader()
        {
            InitializeComponent();
        }
        private void BarcodeReader_Load(object sender, EventArgs e)
        {
            this.KeyDown += new KeyEventHandler(BarcodeReader_KeyDown);
            this.KeyUp += new KeyEventHandler(BarcodeReader_KeyUp);
        }
        private void BarcodeReader_KeyUp(object sender, KeyEventArgs e)
        {
            // if keyboard input is allowed to read
            if (UseKeyboard && e.KeyData != Keys.Enter)
            {
                MessageBox.Show(e.KeyData.ToString());
            }

            /* check if keydown and keyup is not different
             * and keydown event is not fired again before the keyup event fired for the same key
             * and keydown is not null
             * Barcode never fired keydown event more than 1 time before the same key fired keyup event
             * Barcode generally finishes all events (like keydown > keypress > keyup) of single key at a time, if two different keys are pressed then it is with keyboard
             */
            if (cforKeyDown != (char)e.KeyCode || cforKeyDown == '\0')
            {
                cforKeyDown = '\0';
                _barcode.Clear();
                return;
            }

            // getting the time difference between 2 keys
            int elapsed = (DateTime.Now.Millisecond - _lastKeystroke);

            /*
             * Barcode scanner usually takes less than 17 milliseconds as per my Barcode reader to read , increase this if neccessary of your barcode scanner is slower
             * also assuming human can not type faster than 17 milliseconds
             */
            if (elapsed > 17)
                _barcode.Clear();

            // Do not push in array if Enter/Return is pressed, since it is not any Character that need to be read
            if (e.KeyCode != Keys.Return)
            {
                _barcode.Add((char)e.KeyData);
            }

            // Barcode scanner hits Enter/Return after reading barcode
            if (e.KeyCode == Keys.Return && _barcode.Count > 0)
            {
                string BarCodeData = new String(_barcode.ToArray());
                if (!UseKeyboard)
                    MessageBox.Show(String.Format("{0}", BarCodeData));
                _barcode.Clear();
            }

            // update the last key press strock time
            _lastKeystroke = DateTime.Now.Millisecond;
        }

        private void BarcodeReader_KeyDown(object sender, KeyEventArgs e)
        {
            //Debug.WriteLine("BarcodeReader_KeyDown : " + (char)e.KeyCode);
            cforKeyDown = (char)e.KeyCode;
        }
    }

Check Here.. GitHub Link

How to Check If User Input Is from Barcode Scanner or Keyboard