Variadic curried sum function

Question

I need a js sum function to work like this:

sum(1)(2) = 3
sum(1)(2)(3) = 6
sum(1)(2)(3)(4) = 10 
etc.

I heard it can\'t be done. But heard

Answer 1

Here is another functional way using an iterative process

const sum = (num, acc = 0) => {
    if (!num) return acc;
    return x => sum(x, acc + num)
}

sum(1)(2)(3)()

and one-line

const sum = (num, acc = 0) => !num ? acc : x => sum(x, acc + num)

sum(1)(2)(3)()