타입스크립트 Typescript 함수

Typescript

// 함수

function hello(name:string, age?:number): string {

    if (age !== undefined) {

        return `Hello, ${name}. You are ${age}.`;

    } else {

        return `Hello, ${name}.`;

    }

}

console.log(hello("Same", 30));

console.log(hello("Same"));

//let test:number = hello("Same", 30); 에러발생 타입 불일치

let test2:string = hello("Same", 30);

// 오버로드

interface User {

    name: string;

    age: number;

}

function join(name: string, age: string): string;

function join(name: string, age: number): User;

function join(name: string, age: string|number): User|string {

    if (typeof age === "number") {

        return {

            name,

            age,

        };

    } else {

        return "나이는 숫자로 입력해주세요.";

    }

}

const sam: User = join("Sam", 30);

const jane: string = join("Jane", "30");