7-8编程练习

来源：7-8 编程练习

weixin_慕婉清6311724

2019-08-11 22:15:54

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
 <title>Document</title>
    <script type="text/javascript" src="index.js"></script>
</head>
<body onload="address()">
 <form>
   省份：<select name="province" id="province" onchange="linkage()"></select>
   市/区：<select name="city" id="city"></select>
 </form>
</body>
</html>

function address(){
    var sf=document.getElementById("province");
    var arraySf=new Array("北京市","天津市","河北省","河南省");
    for(var i=0;i<=arraySf.length-1;i++){
        selectAdd(sf,arraySf[i],i);
    }
}
function selectAdd(obj,name,value){
 obj.options.add(new Option(name,value));
}
function linkage(){
    var sf=document.getElementById("province");
    var city=document.getElementById("city");
    if(sf.value==0){
        city.options.length=0;
        selectAdd(city,"朝阳区",0);
        selectAdd(city,"西城区",1);
    }else if(sf.value==1){
        city.options.length=0;
        selectAdd(city,"西青区",2);
        selectAdd(city,"武清区",3);
    }else if(sf.value==2){
        city.options.length=0;
        selectAdd(city,"石家庄",4);
        selectAdd(city,"邯郸市",5);
    }else if(sf.value==3){
        city.options.length=0;
        selectAdd(city,"郑州市",6);
        selectAdd(city,"开封市",7);
    }
}

添加城市的时候怎样优化呢

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