Province and city linkage code based on jquery & json_jquery

< ;script src="/Scripts/script.js" type="text/javascript">

Demo:

Please select a province


Please select a city


Please select the district and county

/*
author: elycir
create: 2012-06
description: Provincial and municipal level three (secondary) linkage
* /
$(function () {
var citySelector = function () {
var province = $("#province");
var city = $("#city");
var district = $("#district");
var preProvince = $("#pre_province");
var preCity = $("#pre_city");
var preDistrict = $("# pre_district");
var jsonProvince = "/content/json-array-of-province.js";
var jsonCity = "/content/json-array-of-city.js";
var jsonDistrict = "/content/json-array-of-district.js";
var hasDistrict = true;
var initProvince = "Please select a province ";
var initCity = "Please select a city";
var initDistrict = "Please select a district or county ";
return {
Init: function () {
var that = this;
that._LoadOptions(jsonProvince, preProvince, province, null, 0, initProvince);
province.change(function () {
that._LoadOptions(jsonCity, preCity, city, province, 2, initCity);
});
if (hasDistrict) {
city.change (function () {
that._LoadOptions(jsonDistrict, preDistrict, district, city, 4, initDistrict);
});
province.change(function () {
city.change() ;
});
}
province.change();
},
_LoadOptions: function (datapath, preobj, targetobj, parentobj, comparelen, initoption) {
$. get(
datapath,
function (r) {
var t = ''; // t: html container
var s; // s: selected identifier
var pre; // pre: initial value
if (preobj === undefined) {
pre = 0;
} else {
pre = preobj.val();
}
for (var i = 0; i < r.length; i ) {
s = '';
if (comparelen === 0) {
if (pre !== "" && pre !== 0 && r[i].code === pre) {
s = ' selected="selected" ';
pre = '';
}
t = '' r[i].name '';
}
else {
var p = parentobj.val();
if (p.substring(0, comparelen) === r[i].code.substring(0, comparelen)) {
if (pre !== "" && pre !== 0 && r[i] .code === pre) {
s = ' selected="selected" ';
pre = '';
}
t = '' r[i].name '';
}
}

}
if (initoption !== '') {
targetobj.html(initoption t);
} else {
targetobj.html(t);
}
},
"json"
);
}
};
} ();
citySelector.Init();
});