CODEWITHSUNDEEP
javascriptrecursion
allanberry
allanberry

Reputation: 7765

create object from array, using recursion/reduce?

I'm just kind of lousy with recursive functions.

I want to turn this...

const input = { regions: ["US", "CA", "LA"], checked: true };

...into the following, using recursion and reduce:

const output = {
  US: {
    CA: {
      LA: true
    }
  }
};

Help? I've tried lots of things, but my experiments are too embarrassing to share.

Upvotes: 0

Views: 137

Answers (2)

Nick Parsons
Nick Parsons

Reputation: 50759

You don't need recursion here (and I would favour .reduceRight), but, here is a different approach which uses a recursive function in case you're interested in how it could be done. You can destructure the first element from your array and use it as the key, then, set the value to the next call which would produce an object. If no key can be retrieved, you can return the value of checked:

const input = { regions: ["US", "CA", "LA"], checked: true };
const getNested = ([key, ...r], end) => key ? {[key]: getNested(r, end)} : end;

console.log(getNested(input.regions, input.checked));

Upvotes: 2

CertainPerformance
CertainPerformance

Reputation: 370789

Iterate over the regions with reduceRight, creating the nested object with an initial value of the checked property, and surrounding it with the new object (the new accumulator) on every iteration:

const input = { regions: ["US", "CA", "LA"], checked: true };
const { regions, checked } = input;

const output = regions.reduceRight((a, prop) => ({ [prop]: a }), checked);
console.log(output);

Upvotes: 3

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