url编码时怎么让其编码结果为gbk而不是utf8的

var querystring = require("querystring");
var data = {"username": "张三", "password": "12345"};
var content = querystring.stringify(data);
console.log(content);

输出结果为:username=%E5%BC%A0%E4%B8%89&password=12345

怎么让其结果显示:

username=%D5%C5%C8%FD&password=12345