JSON.stringify()方法第三个参数问题！

利用stringify()方法，return underfined;可以过滤key为name的键，但是一下过滤了所有key为name的键，怎么控制只过滤company对象下面的name呢？

var person = {
            name: "张三",
            age: 14,
            sex: "男",
            tell: 5033453,
            birthday:new Date(),
            company:{
                name:"百度",
                contry:"中国",
                boss:"马化腾",
                state:1
            }
        };

        var jperson = JSON.stringify(person,function(key,value){
            switch (key) {
                case "name":
                    return undefined;
                case "state":
                    return value===1?"通过":"未通过";
                case "birthday":
                    return value.replace("T"," ").replace("Z","").substr(0,19);
                default:
                    return value;
            }

        });
        console.log(jperson);
结果：{"age":14,"sex":"男","tell":5033453,"birthday":"2016-05-10 10:48:54","company":{"contry":"中国","boss":"马化腾","state":"通过"}}