js中取json对象的键和值

//构建一个json对象
var jb={"美的":49,"三星":35,"海信":25,"格力":16,"方太":14};

for(var key in jb){
   alert(key);//json对象的key
   alert(jb[key]);//json对象的值
}

js取数组的索引和值

//构建一个数组
var areaTable = new Array();
areaTable["1100"] = "北京市"
areaTable["1200"] = "天津市"
areaTable["1300"] = "河北省"
areaTable["1400"] = "山西省"
areaTable["1500"] = "内蒙古自治区"

for(index in areaTable)
    {
        var temp = {};
        temp["areaID"] = index.toString();
        temp["areaName"] = areaTable[index].toString();
        datum.push(temp);
    }