Hey nauna,
Please refer below sample.
HTML
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?libraries=places"></script>
<script type="text/javascript">
    window.onload = function () {
        var postal = document.getElementById('txtPostalCode');
        var options = { types: ['(regions)'] }
        var autocomplete = new google.maps.places.Autocomplete(postal, options);
        google.maps.event.addListener(autocomplete, 'place_changed', function () {
            var location = autocomplete.getPlace();
            geocoder = new google.maps.Geocoder();
            console.log(location['geometry'])
            lat = location['geometry']['location'].lat();
            lng = location['geometry']['location'].lng();
            var latlng = new google.maps.LatLng(lat, lng);
            geocoder.geocode({ 'latLng': latlng }, function (results) {
                for (i = 0; i < results.length; i++) {
                    for (var j = 0; j < results[i].address_components.length; j++) {
                        for (var k = 0; k < results[i].address_components[j].types.length; k++) {
                            if (results[i].address_components[j].types[k] == "postal_code") {
                                zipcode = results[i].address_components[j].short_name;
                                postal.value = zipcode;
                            }
                        }
                    }
                }
            });
        });
    }
</script>
<input id="txtPostalCode" type="text" size="50" autocomplete="off" />
Screenshot
