省市区三级联动，JS实现

function cmbAddOption(cmb, str, obj) {
var option = document.createElement("OPTION");
cmb.options.add(option);
option.innerHTML = str;
option.value = str;
option.obj = obj;
}

 function change() {
            //异步加载所有医院、自定义方法
            var provinceName = $("#provinceName").val();
            var cityName = $("#cityName").val();
            var areaName = $("#areaName").val();
            var bat = { "provinceName": provinceName, "cityName": cityName, "areaName": areaName };
            $.post("/Regist/GetHospital", bat, function (data) {
                var objList = JSON.parse(data);
                $("#FwName").find("option").remove();
                for (var i = 0; i < objList.length; i++) {
                    var FwName = document.getElementById("FwName");
                    cmbAddOption(FwName, objList[i].hospitalValue, objList[i].hospitalTxt)
                }
            });
        }