JavaScript barcode scanner detector

BarcodeScanner.js

function BarcodeScannerDetector(options) {
    this.options = options || {}; // Default
    this.options.keypressDelay = this.options.keypressDelay || 100; // Delay between press
    this.chars = []; // Our barcode
    this.events();
}

BarcodeScannerDetector.prototype.delay = function(callback, ms) {
    clearTimeout(this.timer);
    this.timer = setTimeout(callback, ms);
};

BarcodeScannerDetector.prototype.events = function() {
    var _this = this;
    window.onkeypress = function(e) {
        if (e.which >= 48 && e.which <= 57) {
            _this.chars.push(String.fromCharCode(e.which));
            _this.delay(function() {
                if (_this.chars.length >= 10) {
                    console.log("Barcode scanned: " + _this.chars.join(""));
                }
                _this.chars = [];
            }, _this.options.keypressDelay);
        }
    };
};

new BarcodeScannerDetector(); // init