基于外部一个省市联动js框架，实现初始化特定的地址级联

今天在项目中遇见这样一个问题，省市联动是采用网上的一个js框架，很好用，也很方便，这个省市联动最开始的样子长这样



现在实现一个更新个人地址功能，因为后台数据库是有原地址的，所以希望省市联动的三个下拉框的初始值是原地址



这里有几个问题需要解决，首先更改被选中的值。这可以通过改变selected的值为true实现，貌似，我们只需要改变省，市，区三个下拉框的被选中值就可以实现这个功能，但是，这里有个问题

function change(v){
var str="0";
for(i=0;i<v;i++){
str+=("_"+(document.getElementById(s[i]).selectedIndex-1));
};
var ss=document.getElementById(s[v]);
with(ss){
length = 0;
options[0]=new Option(opt0[v],opt0[v]);
if(v && document.getElementById(s[v-1]).selectedIndex>0 || !v){
if(dsy.Exists(str)){
ar = dsy.Items[str];
for(i=0;i<ar.length;i++){
options[length]=new Option(ar[i],ar[i]);
}//end for
if(v){ options[0].selected = true; }
}
}//end if v
if(++v<s.length){change(v);}
}//End with
}
var dsy = new Dsy();

dsy.add("0",["北京市","天津市","上海市","重庆市","河北省","山西省","内蒙古","辽宁省","吉林省","黑龙江省","江苏省","浙江省","安徽省","福建省","江西省","山东省","河南省","湖北省","湖南省","广东省","广西","海南省","四川省","贵州省","云南省","西藏","陕西省","甘肃省","青海省","宁夏","新疆","香港","澳门","台湾省"]);
dsy.add("0_0_0",["东城区","西城区","崇文区","宣武区","朝阳区","丰台区","石景山区","海淀区","门头沟区","房山区","通州区","顺义区","昌平区","大兴区","怀柔区","平谷区","密云县","延庆县","延庆镇"]);
dsy.add("0_0",["北京市"]);
dsy.add("0_1_0",["和平区","河东区","河西区","南开区","河北区","红桥区","塘沽区","汉沽区","大港区","东丽区","西青区","津南区","北辰区","武清区","宝坻区","蓟县","宁河县","芦台镇","静海县","静海镇"]);
dsy.add("0_1",["天津市"]);
dsy.add("0_2_0",["黄浦区","卢湾区","徐汇区","长宁区","静安区","普陀区","闸北区","虹口区","杨浦区","闵行区","宝山区","嘉定区","浦东新区","金山区","松江区","青浦区","南汇区","奉贤区","崇明县","城桥镇"]);
dsy.add("0_2",["上海市"]);
dsy.add("0_3_0",["渝中区","大渡口区","江北区","沙坪坝区","九龙坡区","南岸区","北碚区","万盛区","双桥区","渝北区","巴南区","万州区","涪陵区","黔江区","长寿区","合川市","永川区市","江津市","南川市","綦江县","潼南县","铜梁县","大足县","荣昌县","璧山县","垫江县","武隆县","丰都县","城口县","梁平县","开县","巫溪县","巫山县","奉节县","云阳县","忠县","石柱土家族自治县","彭水苗族土家族自治县","酉阳土家族苗族自治县","秀山土家族苗族自治县"]);
dsy.add("0_3",["重庆市"]);

var s=["s_province","s_city","s_county"];//三个select的name
var opt0 = ["省份","地级市","市、县级市"];//初始值

function _init_area(){  //初始化函数
for(i=0;i<s.length-1;i++){
document.getElementById(s[i]).onchange=new Function("change("+(i+1)+")");
}
change(0);
}

这是省事联动部分代码，dsy数组里面没有全部贴出来，可以看到，初始化函数给每省，市下拉框绑定了个onchange事件函数

这个函数是change(1)，change(2)，这就意味着，每次联动的时候就会调用这两个函数之一，所以要实现这个功能得在每次设置选中值之后加上对应的下拉框的onchange所绑定的函数，change(1)或者change(2)

$("#s_province").val(context.eq(0).html());
change(1);
$("#s_city").val(context.eq(1).html());
change(2);
$("#s_county").val(context.eq(2).html());

这样就能实现特定地址初始化，并能直接产生级联效果，否则单单设置被选中值，虽然能达到特定地址初始化，但确无法产生级联效果，即，省确实是江西省，但是市这个下拉框无法显示所有江西省的市区！

结尾：虽然可能大家使用的省市联动的外部js框架不同，实现这个特定地址初始化的功能原理相同，即，先设置被选中值，然后调用之前框架绑定在onchange上的函数！