function validateForm() {
    zipValue = document.form.zip.value;
    if (isZipcode(zipValue)) {
        document.form.submit();
    } else {
        alert("To proceed please enter a valid ZIP Code.");
        return false
    }
}

function isZipcode(value) {
    var exp_zipcode = /^[0-9]{5}$/;
    return exp_zipcode.test(value);
}

function validateCurrentForm(currentForm) {
    var elementsInputs;
    elementsInputs = currentForm.getElementsByTagName("input");
    for (var intCounter = 0; intCounter < elementsInputs.length; intCounter++) {
        if (elementsInputs[intCounter].name == "ZipZip") {
            if (!(isZipcode(elementsInputs[intCounter].value))) {
                alert("To proceed please enter a valid ZIP Code.");
                elementsInputs[intCounter].focus();
                return false;
            }
        }
    }
    return true;
}

function clearZipValue(zipInput) {
    if (isZipcode(zipInput.value)) {
        zipInput.select();
    } else {
        zipInput.value = '';
    }
}

function getZipValue(zipInput) {
    if (!isZipcode(zipInput.value)) {
        zipInput.value = "ZIP Code...";
    }
}