Google Places API (get all postal code around me) - api

Question

I am using the blowing script to get all store around position wit 20 mile and working well but when try to using it to get postal_code do not working
how i get all postal code around center with specific distance
code:
<script type="text/javascript" language="javascript">
var lat = "";
var lng = "";
function latClick(glocation) {
var a = new google.maps.Geocoder();
a.geocode({ 'address': glocation }, function (results, status) {
if (status == google.maps.GeocoderStatus.OK)
var c = results;
else
c = "We couldn't find that location. Please try again."
lat = c[0].geometry.location.lat();
lng = c[0].geometry.location.lng();
var pyrmont = new google.maps.LatLng(lat, lng);
//sll=30.04443,31.234217&sspn=0.036703,0.084543&geocode=FU1wygEdO5jcAQ%3BFQRxygEdgJ7cASnrviELpj9YFDG6O0LolrLfeQ&mra=mift&
map = new google.maps.Map(document.getElementById('map'), {
mapTypeId: google.maps.MapTypeId.ROADMAP,
center: pyrmont,
zoom: 15
});
var request = {
location: pyrmont,
radius: 200,
types: ['store']
};
infowindow = new google.maps.InfoWindow();
var service = new google.maps.places.PlacesService(map);
service.nearbySearch(request, callback);
});
}
var map;
var infowindow;
function initialize() {
latClick("Jersey City, NJ 07306, United States");
}
function callback(results, status) {
var x = "";
if (status == google.maps.places.PlacesServiceStatus.OK) {
for (var i = 0; i < results.length; i++) {
createMarker(results[i]);
x = x + results[i].name + ", ";
}
alert(x);
}
}
function createMarker(place) {
var placeLoc = place.geometry.location;
var marker = new google.maps.Marker({
map: map,
position: place.geometry.location
});
google.maps.event.addListener(marker, 'click', function() {
infowindow.setContent(place.name);
infowindow.open(map, this);
});
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>