[typescript] function type

function type을 만드는 간단한 예제코드

type CallbackFn = (arg: string) => number;

// anonymous arrow function
const test: CallbackFn = (str) => {
    console.log(str);
    return Number(str);
}

// anonymous function
const test2: CallbackFn = function(str) {
    console.log(str)
    return Number(str)
}

// class method
interface FooTypes {
    foofun: CallbackFn;
}

class TestFoo implements FooTypes {
    constructor() {}
    foofun(str: string) {
        console.log(str)
        return Number(str);
    }
}

test('111'); // 111
test2('222'); // 222
const testFoo = new TestFoo();
testFoo.foofun('333') // 333