nodejs渐入佳境[3]-require导入模块

require 导入其他文件

require可以执行其他文件的内容。

新建文件: nodes.js:

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

app.js:

//打印字符串
console.log('Start app.');

const nodes = require('./nodes.js')
//导入node自带modules，fs文件操作
const fs = require('fs');
//os系统操作
const os = require('os');
//获取系统名字
var user = os.userInfo();

//添加字符串到回调函数中，并执行回调函数。出错就会报错，不出错就会打印出'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!');
}
);

打开控制台，在当前目录下输入：

> node app.js

输出字符串

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

require 导入属性

nodes.js:

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

module.exports.age = 25;

app.js:

//打印字符串
console.log('Start app.');

const nodes = require('./nodes.js')
//导入node自带modules，fs文件操作
const fs = require('fs');
//os系统操作
const os = require('os');
//获取系统名字
var user = os.userInfo();

//添加字符串到回调函数中，并执行回调函数。出错就会报错，不出错就会打印出'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!');
}
);

打开控制台，在当前目录下输入：

> node app.js

文件中存储：Hello jackson age 25

require 导入函数

nodes.js:

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

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

app.js:

console.log('Start app.');

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

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

打开控制台，在当前目录下输入：

> node app.js

输出字符串

Start app.
start nodes.js
addNode
New Node

require 导入带参函数

nodes.js:

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

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

  return a+b;
};

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

app.js:

//打印字符串
console.log('Start app.');

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

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

打开控制台，在当前目录下输入：

> node app.js

输出字符串

Start app.
start nodes.js
3