✏️ 1.

interface Add {
  //(첫번째 인자: type, 두번째 인자: type): return 값 type
  (num1: number, num2: number): number
}

적용하기

const addFunction: Add = function(x, y) {
  return x + y;
}

addFunction(10, 20)

✏️ 2.

interface IsAdult {
  (age: number):boolean
}

const calculateAge:IsAdult = (age) => {
  return age > 19
}

calculateAge(10)