autocomplete city based on zip code / Autovervollständigung Ort bzw. Stadt anhand Postleitzahl

zip2city.js

$('#zip').blur(function() {
	var city = $('#city');
	if (!city.val()) {
		$.getJSON('http://www.geonames.org/postalCodeLookupJSON?&country=DE&callback=?', {postalcode: this.value }, function(response) {
			if (!city.val() && response && response.postalcodes.length && response.postalcodes[0].placeName) {
				city.val(response.postalcodes[0].placeName);
			}
		})
	}
});