function validatezip() {
    var zipcode = document.getElementById("zipcodeinput").value;
    var zipcodeform = document.getElementById("zipcodeform");
    var zipPattern = new RegExp("^\\d{4}$");
    var outputElement = document.getElementById("zipcodeerror");
    if(!zipPattern.test(zipcode)) {
        outputElement.innerHTML = document.getElementById("hiddenErrorCode").value;
        return false;
    }
    else {
        outputElement.innerHTML = "";
        zipcodeform.submit();
    }
}