Node js导出模块在Promise中设置变量不起作用

Question

我正在使用Promise进行获取请求。我无法使用请求中返回的JSON数组更新全局变量记录

 app.js
    class Token {
    constructor(){
        this.key = "some";
    }
}
module.exports = new Token();

index.js

let My= require('./app')
    setToken(){
            return new Promise(resolve => {
                this.getToken().then((data) => { //return key
                    if(data){
                        let gotToken = data;
                        My.key    = gotToken.token
                        console.log(My.key) //  print key 
                        resolve(true);
                    }
                })
            });
        }
in another  function

console.log(My.key) // print some