a.js
這是node導出一個類
let Person = function () {

this.name = '張三;

}
Person.prototype = {

constructor:Person,
say:function () {
    console.log('my name is '+this.name);
}

};
module.exports.Person = Person;
b.js
引用a.js文件
let Person = require("./a.js");
let person = new Person('張三');
console.log(person.say());

為什么最后輸出 my name is 張三 和undefined