Need to use a function inside the map of a list

Question

I'm just learning JavaScript and I'm trying to do the following. Let's say I have the following function:

f(a,b) {return(a+b)}

And now I have a list of for example the following:

list = [1,2,3]

What I would like to do is map for that list in which I call the function above f with a predefined value and each value of the list. I've tried this:

listB = list.map(x => f(x+23))

But it returns a NaN, and if I add some brackets that snippet returns undefined.

What's going on and how can I solve it?

Answer 1

you have error in your function call f(x + 23). This is because your function f expects 2 arguments, and you forward only one. number + undefined -> NaN

Answer 2

you can re-write it as

const list = [1, 2, 3, 4];
const listb = list.map(f);

function f(num) {
  return num + 23;
}