console.log('start nodes.js');

//列印字串
console.log('Start app.');

const nodes = require('./nodes.js')
//匯入node自帶modules，fs檔案操作
const fs = require('fs');
//os系統操作
const os = require('os'
 
);
//獲取系統名字
var user = os.userInfo();

//新增字串到回撥函式中，並執行回撥函式。出錯就會報錯，不出錯就會打印出'The "data to append" was appended to file!'
fs.appendFile('greetings.txt',`Hello ${user.username}`,(err) => {
  if (err) throw err;
  console.log('The "data to append" was appended to file!');
}
);

> node app.js

Start app.
start nodes.js
The "data to append" was appended to file!

console.log('start nodes.js');

module.exports.age = 25;

//列印字串
console
 
.log('Start app.');

const nodes = require('./nodes.js')
//匯入node自帶modules，fs檔案操作
const fs = require('fs');
//os系統操作
const os = require('os');
//獲取系統名字
var user = os.userInfo();

//新增字串到回撥函式中，並執行回撥函式。出錯就會報錯，不出錯就會打印出'The "data to append" was appended to file!'
fs.appendFile('greetings.txt',`Hello ${user.username} age ${nodes.age}`,(err) => {
  if (err) throw err;
  console.log('The "data to append" was appended to file!');
}
);

> node app.js

console.log('start nodes.js');

module.exports.addNote = ()=>{
  console.log('addNode');
  return 'New Node';
};

console.log('Start app.');

const nodes = require('./nodes.js')

 const res = nodes.addNote();
console.log(res);

> node app.js

Start app.
start nodes.js
addNode
New Node

console.log('start nodes.js');

module.exports.add = (a,b)=>{

  return a+b;
};

module.exports.addNote = ()=>{
  console.log('addNode');
  return 'New Node';
};

//列印字串
console.log('Start app.');

const nodes = require('./nodes.js')

 const res = nodes.add(1,2);
console.log(res);

> node app.js

Start app.
start nodes.js
3