function getLabelForId(id) {
    var label, labels = document.getElementsByTagName('label');
    for (var i = 0; (label = labels[i]); i++) {
        if (label.htmlFor == id) return label;
    }
    return false;
}
function checkzipcode() {
    var zipcode = document.getElementById('zipcode');
    var label = getLabelForId('zipcode');
    var digits = zipcode.value.replace(/[^0-9]/ig, '');
    if (!digits) {
        label.className = '';
        zipcode.value = '';
        return;
    }
    if (digits.length == 5) {
        zipcode.value = digits.substring(0, 5);
    } else {
        zipcode.value = digits;
    }
}

function CheckSearch(theForm)
{
if (theForm.zipcode.value.length < 5)
  {
    alert("Please enter a Zip Code.");
    theForm.zipcode.focus();
    return false;
  }

  return (true);
}