[Type Script]デフォルトタイプ

基本タイプ

String

let str: string = 'hi';

Number

let num: number = 10;

Boolean

let isLoggedIn: boolean = false;

Object

Array

let arr: number[] = [1,2,3];
let week1: string[] = ['mon', 'tue', 'wed'];

let arr: Array<number> = [1,2,3];
let week2: Array<string> = ['mon', 'tue', 'wed'];

let arr: [string, number] = ['hi', 10];

arr[1].concat('!');
// Error, 'number' does not have 'concat'
arr[5] = 'hello';
// Error, Property '5' does not exist on type '[string, number]'.

enum Avengers { Capt, IronMan, Thor }
let hero: Avengers = Avengers.Capt;

enum Avengers { Capt, IronMan, Thor }
let hero: Avengers = Avengers[0];

enum Avengers { Capt = 2, IronMan, Thor }
let hero: Avengers = Avengers[2];
// Capt
let hero: Avengers = Avengers[4];
// Thor

Any

let str: any = 'hi';
let num: any = 10;
let arr: any = ['a', 2, true];

Void

let unuseful: void = undefined;
function notuse(): void {
	console.log('sth');
}

Never

// 이 함수는 절대 함수의 끝까지 실행되지 않는다는 의미
function neverEnd(): never {
  while (true) {
    
  }
}

function showError(){
  throw new Error();
}