how to validate Indian IFSC code(SBIN0015916) code on key press event in javascript.

$(document).ready(function () {
        $('#TextBoxID').keypress(function (event) {
            var keycode = (event.keyCode ? event.keyCode : event.which);
            var TextValue = document.getElementById("TextBoxID").value;
            var firstFourLetter =  TextValue.substring(1,4); 
            var lastFourLetter = TextValue.substring(5,10);
            if (firstFourLetter.keycode >= '65' && lastFourLetter.keycode <= '90') {
                return true;
            }
            return false;
        });
    });