Detect scanner input using jquery

Question

Suppose I have two textboxes:

Answer 1

Going off the idea I suggested in the comments, I came up with this...

var _keybuffer = "";

$(document).on("keyup", function(e) {
    var code = e.keyCode || e.which;
    _keybuffer += String.fromCharCode(code).trim();
    // trim to last 13 characters
    _keybuffer = _keybuffer.substr(-13);

    if (_keybuffer.length == 13) {
        if (!isNaN(parseInt(_keybuffer))) {
            barcodeEntered(_keybuffer);
            _keybuffer = "";
        }
    }
});

function barcodeEntered(value) {
    alert("You entered a barcode : " + value);
}

It keeps a buffer of the last 13 keys pressed and if it's just numbers then it assumes it's a barcode and triggers the barcodeEntered function. This is obviously a hack and assumes that there is no reason anyone would ever type a 13 figure number elsewhere on the page (but you could make it ignore key presses if certain fields had focus etc..)

It captures all key presses on the page, regardless of focus so it should capture you scanning a barcode even when nothing has focus.

Edit: I've added .trim() to the keyboard buffering so that spaces are ignored, as per suggestion from @DenisBorisov.