Need to use a function inside the map of a list-CodePudding

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?

CodePudding user response：

Should be f(x, 23) instead of f(x 23):

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

listA = [1,2,3]
listB = listA.map(x => f(x,23))

console.log(listB)

CodePudding user response：

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

CodePudding user response：

you can re-write it as

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

function f(num) {
  return num   23;
}