타입스크립트.

그냥 기본.

let 이름: string = "kim";
let 나이: number = 50;
let 결혼했니: boolean = false;
let 결혼했니2: undefined = undefined;
let 회원들: string[] = ["kim", "park"];
let 회원들2: { name: string; age: number } = { name: "kim", age: 30 };
let project: { member: string[]; days: number; started: boolean } = {
  member: ["kim", "park"],
  days: 30,
  started: true,
};

유니온

let kakouser: number | string = "kim";
kakouser = 123;

let users: (number | string)[] = [1, "2", 3];
let 오브젝트: { a: string | number } = { a: "123" };

any, unknown

let username: any; //이럴거면 typescript 기능을 없애는것.
username = 123;
username = [];

let username2: unknown;
username2 = 123;
username2 = [1, 2, 3];

function nameWrite(x?: string) {
  if (typeof x === "string") {
    console.log("안녕하세요" + x);
  } else {
    console.log("이름이 없습니다");
  }
}

function parameterLength(x: string | number) {
  console.log(x.toString().length);
}

unction 결혼가능섣테스트(
  월소득: number,
  집보유: boolean,
  매력점수: string
): string | void {
  if (집보유) {
    var havHouseScore = 500;
  }
  if (매력점수 === "상") {
    var attactionScore = 100;
  }
  if (월소득 + havHouseScore + attactionScore > 600) {
    return "결혼가능";
  }
}

console.log(결혼가능섣테스트(700, false, "중"));