[WorM32]

<input type="text" class="barcode">
<script>var barcode= document.getElementsByClassName('barcode')[0],
    barcodeTimeoutId;
barcode.addEventListener('keyup', function () {
    clearTimeout(barcodeTimeoutId);
    barcodeTimeoutId = setTimeout(function () {
        alert('Прошло 2 сек. после ввода');    
    }, 2000);
}, true);</script>