Javascript: How to convert and map an object containing objects into an array?

Question

In Javascript, how to map and convert this object:

  {
    0: {k1 : v1},
    2: {k2 : v2}
  }

to this array:

[
    {
        label: k1,
        value: v1
    },
    {
        label: k2,
        value: v2
    }
]

obs.: one-liners are nice, but all answers are welcome.

I couldn't get the desired result, but I have blindly followed formulas like:

const objectMap = (obj, fn) =>
  Object.fromEntries(
    Object.entries(obj).map(
      ([k, v], i) => [i, fn(v, k, i)]
    )
  )
const cfieldsFinal = objectMap(modcf, (k, v) => ({
  label: v,
  value: k
}))

and that's ALMOST what I need, except, it's still an object:

output => {0: {label: k1, value: v1}, 1: {label: k2, value:  v2}}

So, only a complete noob such as myself would get stuck on this part...

Ori Drori · Accepted Answer · 2020-01-08 23:11:29Z

2

You're very close, you just need to construct the object manually. Start by using Array.values() to convert data to an array. Iterate the array with Array.flatMap() to flatten the sub-arrays create by the internal map. Convert each object to an array of [key, value] pairs. Map each pair, and create an object.

const data = {0: { k1: 'v1' }, 2: { k2: 'v2' }}

const result = Object.values(data) // convert data to an array
  .flatMap(o => // map to a flattend array
    Object.entries(o) // get the entries of each object 
      .map(([label, value]) => ({ label, value })) // create a new object from each entry
  )
  
console.log(result)

answered Jan 8, 2020 at 23:11

Ori Drori

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2 Comments

mirage Over a year ago

Thank you both, Ori and zero298. No wonder I couldn't simply have deduced a way to do something apparently so trivial...

Ori Drori Over a year ago

You're welcome. Don't be afraid to ask/answer. Some things that seem trivial now, took time to learn and evolve.

zero298 · Accepted Answer · 2020-01-08 23:09:52Z

0

const foo = {
  0: {
    k1: "v1"
  },
  2: {
    k2: "v2"
  }
};

/*
[
    {
        label: k1,
        value: v1
    },
    {
        label: k2,
        value: v2
    }
]
*/

const oe = Object.entries;
const bar = oe(foo).map(([k, v]) => {
  const [label, value] = oe(v)[0];
  return {
    label,
    value
  };
});

console.log(bar);

answered Jan 8, 2020 at 23:09

zero298

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