TypeScript

npm install typescript --save-dev
yarn add typescript

npm install -g ts-node
yarn add ts-node

tsc --init

{
  "compilerOptions" : {
    // 目標語言: es6, es2015, es2016, es2017, es2018, es2019, es2020
    "target" : "es5",
    "module" : "commonjs",
    // 產生對應原始檔
    "sourceMap" : true,
    "inlineSourceMap" : true,
    // 輸出 js 檔案目錄
    "ourDir" : "./dist",
    // 來源目錄
    "rootDir" : "./src",
    // 移除註解
    "removeComments": true,
    // 不產生 js 檔案
    "noEmit" : true,
    // 錯誤不產生 js 檔案
    "noEmitOnError" : true,

    // 檢查不能有沒有使用的區域變數
    "noUnusedLocals" : true,
    // 檢查不能有沒有使用的函式參數
    "noUnusedParameters" : true,
    // 檢查不能有沒有沒確回傳資料
    "noImplicitReturns" : true,
  },
  // 排除編譯的目錄檔案
  "exclude" : [
    "test.ts",
    "*.dev.ts",
    "**/*.dev.ts",
    "node_modules",
  ],
  // 要編譯的目錄檔案
  "include" : [
    "app.ts",
  ]
}

# 直接執行 typescript 檔案
ts-node app.ts

# 編譯 typescript 檔案
tsc app.ts
# 編譯 typescript 檔案，並監看是否有異動自動重新編譯
tsc app.ts --watch
tsc app.ts --w

let addNumber: Function;
let addNumber: (a: number, b: number) => number;
let num: number;
let name: string = 'KJ';
let name: string | number = 'KJ';
let n: null = null;
let nn: undefined = undefined;
let test: any;
let arr: string[] = ['a', 'b'];
let arr: string[][] = [['a', 'b']];
let tup : [number, string, boolean] = [1, 'a', true]
let tup : [string, string][] = [['a', 'b'], ['c', 'd']]

function printNumber(num: number): void {
  console.log(`Result: ${num}`);
}

function addAndCallback(num1: number, num2: number, cb: (num: number) => void) {
  const result = num1 + num2;
  cb(result);
}

// num2 有加 ?，所以表示可傳可不傳
function printNumber(num: number, num2?: number): void {
  console.log(`Result: ${num}`);
}

enum Role {
  ADMIN,
  READ_ONLY,
  AUTHOR
}

enum Role {
  ADMIN = '33',
  READ_ONLY = '44',
  AUTHOR = '55',
}

// 使用 Enum 變數
if (user.role == Role.ADMIN) {

}

type MyCustomType = number;
type MyCustomType = number | string;
type MyCustomType = 'Kay' | 'Jay';

function(num: MyCustomType) {

}

interface Employee {
  name: string;
  age: number;
}

interface Employee {
  // ? 允許 undefined
  desc?: string;
}

interface CarProps {
  name: string
  age: number
}

class Car implements CarProps {
  name: string
  age: number

  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }
}

type Employee = {
  name: string;
  age: number;
}

const obj : Employee = {
  name: 'KJ',
  age: 17,
};

type Data = {
  userId: number,
  id: number,
  title: string,
  completed: boolean
}


async getData = () => {
  const res = await fetch('https://jsonplaceholder.typicode.com/todos/1');
  const data = await res.json() as Data;
}

const data1 = Data {
  "userId": 1,
  "id": 1,
  "title": "delectus aut autem",
  "completed": false
};

type Beta = {
  name: string
}

const beta = data1 as unknown as Beta;

class Live {
  public roomName: string
  private id: string
  protected name: string

  constructor( room_name: string, room_id: string, holder_name: string) {
    console.log('建立直播');
    this.roomName = room_name;
    this.id = room_id;
    this.name = holder_name;
  }
}

const live = new Live('LOL 直撥', '001', 'Kay');
console.log(live);

class LolLive extends Live {
  constructor( room_name: string, room_id: string, holder_name: string) {
    super(room_name, room_id, holder_name);
  }

  start() {

  }
}

const LolLive = new LolLive('LOL 直撥 2', '002', 'Jay');

class GameLive {
  //  私有變數
  #name
  constructor (name : string) {
    this.#name = name;
  }
}

function print<T> (data: T) {
  console.log('data', data);
}

print<number>(777);
print<string>('KJ');
print<boolean>(true);

class Print<T> {
  data: T
  constructor(d: T) {
    this.data = d;
  }
}

const p = new Print<number>(999)
const p = new Print<string>('KJ')