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Function Type

• 함수 선언식에서 type 지정 가능.

function 함수(a: string): number {
  return 100;
}

• 함수 타입도 type alias 설정 가능.
• 단, 함수 표현식만 가능.

type 함수타입 = (a: string) => number;
const 함수2: 함수타입 = function (x) {
  return 100;
};

const 함수2: 함수타입 = (x) => 100;

• Arrow Function도 사용 가능.

type 함수타입 = (a: string) => number;
const 함수2: 함수타입 = (x) => 100;

methods의 타입

type Member = {
  name: string;
  age?: number;
  plusOne: (x: number) => number;
  changeName: () => void;
};

const 회원정보: Member = {
  name: 'kim',
  plusOne(a) {
    return a + 1;
  },
  changeName: () => {
    console.log('안녕');
  },
};

call back

type CutZeroType = (v: string) => string;
const cutZero: CutZeroType = (v) => (v[0] === '0' ? v.slice(1) : v);

type RemoveDashType = (v: string) => number;
const removeDash: RemoveDashType = (v) =>
  Number(
    v
      .split('')
      .filter((v) => v !== '-')
      .join('')
  );

const callBacks = (v: string, fn1: CutZeroType, fn2: RemoveDashType) => fn2(fn1(v));
console.log(callBacks('010-1111-2222', cutZero, removeDash)); // 1011112222 

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