How to satisfy the lint rules 'array-callback-return'?

Question

This is my first cut:

const planLimits = {plan1: {condition1: 50, ...}}

function initialisePlanLimits(planLimits) {
  const limits = new Map();
  Object.keys(planLimits).map((planId) => (
    const limitMap = new Map(Object.entries(planLimits[planId]));
    limits.set(planId, limitMap);
  ));
  return limits;
}

The linter flags this error: error Expected to return a value in this function array-callback-return

So I changed to this version:

function initialisePlanLimits(planLimits) {
  const limits = new Map();
  Object.keys(planLimits).map((planId) => (
    limits.set(planId, new Map(Object.entries(planLimits[planId])))
  ));
  return limits;
}

It throws another error Unexpected parentheses around single function argument having a body with no curly braces arrow-parens

My questions:

1) I reckon I can fix my first version by sticking in a return null within the curry bracket. But is there a better, more elegant way? A bogus return statement does not make sense in this context

2) Why the second version fails? Isn't it equivalent to the first version?

Answer 1

If I use forEach instead of map, it will not cause the array-callback-return lint error

 Object.keys(planLimits).forEach((planId) => (
    const limitMap = new Map(Object.entries(planLimits[planId]));
    limits.set(planId, limitMap);
  ));

Answer 2

Well, accepted answer advocates about using 'forEach,' which is true. Please read below explaination from ESLint documentation,

Array has several methods for filtering, mapping, and folding. If we forget to write return statement in a callback of those, it's probably a mistake. If you don't want to use a return or don't need the returned results, consider using .forEach instead.