目錄：

一、常用 Command Line

二、Node.js

REPL (Read Eval Print Loop / 互動式解釋器)

內建模組 Native Node modules

外載模組 NPM packages (Node Package Manager)

三、Express

建立Local Serve

設定訪問(get)瀏覽器後的response

post: 讓server取得資料

四、nodemon: 可以讓server即時更改的package

一、常用 Command Line

$ ls
$ ls -a (檢視隱藏檔案)
$ cd
$ pwd
$ clear
$ mkdir DOCUMENT
$ touch index.js
$ start index.js
$ node server.js
$ rm server.js
$ rm -rf DOCUMENT

$ atom .
$ start atom index.js

// ctrl + a (move cursor to beginning)
// ctrl + e (move cursor to end)
// ctrl + c (cancel)
// ctrl + u (delete)

二、Node.js

01. REPL (Read Eval Print Loop / 互動式解釋器)

// 在terminal上執行js
$ node index.js

// 直接以terminal做console(控制台)
$ node

02. Native Node modules 內建 node 模組

可直接在atom中編輯
執行: node index.js

// eg. copy file
// module: fs.copyFileSync(file source, destination)

const fs = require('fs');
fs.copyFileSync("file1.txt", "file2.txt");

03. NPM packages (Node Package Manager) 外部模組

未使用過NPM之檔案需初始化: npm init -y
安裝package: npm install %package%
執行: node index.js

// 初始化 NPM (on terminal)

$ npm init -y
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help init` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (intro-to-node)
version: (1.0.0)
description: This is a intro to node project
entry point: (index.js)
test command:
git repository:
keywords:
author: Penny Lee
license: (ISC)
About to write to C:\Users\Penny\Desktop\intro-to-node\package.json:
Is this OK? (yes)

// eg1. superhero npm: https://www.npmjs.com/package/superheroes
$ npm install superheroes

var superheroes = require("superheroes");
var name = superheroes.random();
console.log(name);

// eg2. supervillains npm: https://www.npmjs.com/package/supervillains
$ npm install supervillains

const supervillains = require("supervillains");
names = supervillains.all;
randomName = supervillains.random();

console.log(randomName);

三、Express

未使用過NPM之檔案需初始化: npm init
在terminal上安裝Express: npm install express
執行: node index.js

01. 建立Local Server

const express = require("express");
const app = express();

app.listen(3000, function(){
  console.log("Server started on port 3000")
});

// terminal上執行
$ node index.js (or nodemon server.js)

建立Local的Server(app)
讓server接通(listen)channel(3000)
執行後可以browser進入route(localhost:3000/)
此時尚未設定server遭訪問時的回應，故會產生以下畫面:

02. 設定訪問(get)瀏覽器後的response

// 在app.listen前插入

app.get("/",function(req, res) {
  console.log(req);
  res.send("hello");
})

app.get("/about",function(req, res) {
  // absolute path
  res.sendFile(__dirname + "/about.html");
})

$ node index.js (or nodemon server.js)

get function設定: 瀏覽器訪問後的回應
first input: 造訪的網頁(target route)，"/"表示主頁，"/about"表示子頁面
second input: 回應函式，自帶req & res參數 function(req, res)
可以針對req設定: eg. console.log(req);
亦可針對res設定: eg. res.send("<h1>HTML code</h1>");
也可以附帶html檔案作為response，但須標示absolute path:
res.sendFile(__dirname + "/index.html");

03. post: 讓server取得資料

未使用過NPM之檔案需初始化: npm init
在terminal上安裝body-parser: npm install body-parser

在index.js上載入body-parser

 const express = require("express");
 const bodyParser = require("body-parser");

 const app = express();

 // pick data comes from HTML form
 // extended: true - allow us to post nested objects
 app.use(bodyParser.urlencoded({extended: true}));

呼叫 post request

 app.post("/", function(req, res){

 // .body 從HTML上取得資料(input)
 console.log(req.body);
 // > { num1: '22', num2: '33', submit: ''}

 var first_num = Number(req.body.num1);
 var second_num = Number(req.body.num2);

 var result = num1 + num2;

 res.send("Calculate result: " + result)
 })