jqueryajax实现下拉框三级无刷新联动,且保存保持选中值状态_jquery

把以下代码放在一个单独的js文件中，在页面上引用即可调用
代码如下:
//获取cookie值
function readCookie(name) {
var cookieValue = "";
var search = name + "=";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search);
if (offset != -1) {
offset += search.length;
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
cookieValue = unescape(document.cookie.substring(offset, end))
}
}

return cookieValue;
}

//保存cookie值
function writeCookie(name, value, hours, escp) {
var expire = "";
if (hours != null) {
expire = new Date((new Date()).getTime() + hours * 3600000);
expire = "; expires=" + expire.toGMTString();
}
if (escp == "True") {
document.cookie = name + "=" + value + expire;
} else {
document.cookie = name + "=" + escape(value) + expire;
}
}

//省市区，流域，水系，断面条件选择
$(function() {

var $ddlprovince = $("#ddlProvince"); //省份
var $ddlcity = $("#ddlCity"); //城市
var $ddlarea = $("#ddlAreaName"); //区域

//根据省份查询城市
//$ddlprovince.focus(); //不要加focus,否则设置selected有问题
$ddlprovince.bind("change keyup", function() {
if ($(this).val() != "-1") {
loadWater($(this).val(), "SelectCity");
} else {
$("select[id$=ddlCity] > option").remove();
$ddlcity.append($("").val("-1").html("--请选择--"));
}
//从新选择省份或者从新选择城市都会初始化区域
$("select[id$=ddlAreaName] > option").remove();
$ddlarea.append($("").val("-1").html("--请选择--"));
});

//如果城市没有填充数据，省份有选择数据则加载数据
if ($("select[id$=ddlCity] > option").length == 1 && $ddlprovince.val() != "-1") {

loadWater($ddlprovince.val(), "SelectCity");
//读cookie,有值则设为选中状态
var cityname = readCookie("JQ_CityName");
if (cityname != null && cityname != "undefined" && cityname != "") {

//$("select[id=ddlWaterXiName] > option:contains('" + watername + "')").attr("selected", "true");
$("select[id$=ddlCity] > option[value='" + cityname + "']").attr("selected", "true");
}
}

//根据城市查询区域
//$ddlcity.focus();
$ddlcity.bind("change keyup", function() {
if ($(this).val() != "-1") {
loadWater($(this).val(), "SelectAreaName");
//选中值存cookie
writeCookie("JQ_CityName", $(this).val(), 0.5, true);
} else {
$("select[name$=ddlAreaName] > option").remove();
$ddlarea.append($("").val("-1").html("--请选择--"));
}
});

//如果区名没有填充数据，城市有选择数据则加载数据
if ($("select[id$=ddlAreaName] > option").length == 1 && $ddlcity.val() != "-1") {
loadWater($ddlcity.val(), "SelectAreaName");
//读cookie,有值则设为选中状态
var areaname = readCookie("JQ_AreaName");
if (areaname != null && areaname != "undefined" && areaname != "") {

$("select[id=ddlAreaName] > option[value='" + areaname + "']").attr("selected", "true");

}
}

$ddlarea.bind("change keyup", function() {
if ($(this).val() != "-1") {
//选中值存cookie
writeCookie("JQ_AreaName", $(this).val(), 0.5, true);
}

});
});

function loadWater(selectedItem, typename) {
$.ajax({
type: "GET",
url: "/GetWaterxiname.ashx",
data: { usetype: typename, id: selectedItem },
contentType: "application/json; charset=utf-8",
dataType: "json",
async: false,
success: function Success(data) {
bindWater(data, typename);
}
});
}

function bindWater(data, typename) {

if (typename == "SelectCity") { //绑定城市

$("select[name$=ddlCity] > option").remove(); //删除原有的option
$("select[id$=ddlCity]").append($("").val("-1").html("--请选择--"));

for (var i = 0; i < data.length; i++) {
$("select[id$=ddlCity]").append($("").val(data[i].City).html(data[i].City));
}
}
else if (typename == "SelectAreaName") {

$("select[name$=ddlAreaName] > option").remove(); //删除原有的option
$("select[id$=ddlAreaName]").append($("").val("-1").html("--请选择--"));

for (var i = 0; i < data.length; i++) {
$("select[id$=ddlAreaName]").append($("").val(data[i].AreaName).html(data[i].AreaName));
}
}
}

说明:省份数据在页面加载时绑定，页面提交后 省份值可以用 selectvalue取，市，区选中数据要用 Request["idname"] 获取