JavaScript: better/cleaner functional way to find item from a nested array

Linda

I am trying to write a find function to find items from matched items from a potentially nested array (without having to flat the array first) and I am trying to write in a FP way.

Here is my attempt:

const nestedArray = [
  [{ id: 1 }],
  [{ id: 2 }],
  [{ id: 3 }, [{ id: 4 }]],
  { id: 5 },
]

function findTarget(arr, predicate) {
  const helper = ([x, ...xs]) =>
    x === undefined
      ? null
      : predicate(x)
      ? x
      : Array.isArray(x)
      ? helper(x) ?? helper(xs)
      : helper(xs)

  return helper(arr)
}

findTarget(nestedArray, (item) => item.id === 5)

I think it works but it is not super readable and I am sure there are better ways to write such a function.