Javascript: 고차 함수

const higherOrderFunc = function() {
    return function() {
        return 12;
    }
}

// which returns below function hence it is higher order function.
higherOrderFunc(); 
> ƒ () {
        return 12;
    }

higherOrderFunc()();
> 12

const testFunc = function(x) {
    return x + 12;
}

//which takes function as an argument.
const higherOrderFunc = function(testFunc) {
    return testFunc(8);
}

higherOrderFunc(testFunc);
> 20

function calculate(operation, numbers) {
    return operation(numbers);
}

function addition(numbers) {
    let sum = 0;
    for (const number of numbers) {
        sum+=number;
    }
    return sum;
}

function multiply(numbers) {
    let sum = 1;
    for (const number of numbers) {
        sum*=number;
    }
    return sum;
}

const numbers = [1,2,3,4,5];
console.log(calculate(addition, numbers));
> 15

console.log(calculate(multiply, numbers));
> 120

calculate(multiply, numbers) - Don't append parenthesis while sending function as an argument.