merge two array objects into one with its own key

Question

I have two objects are contained by an array for each. The following code works. However, I am feeling this code I wrote is a bit odd. I am seeking a better or more standard way to improve below code. Thanks

  const a = [
    {
      apple: '1',
      banana: '2',
    },
  ];

   const b = [
    {
      apples: '1',
      bananas: '2',
    },
  ];

  const json1 = JSON.parse(JSON.stringify(...a));
  const json2 = JSON.parse(JSON.stringify(...b));

  console.log({ ...{a: json1}, ...{b: json2}})

the output needs to be

{
  "a": {
    "apple": "1",
    "banana": "2"
  },
  "b": {
    "apples": "1",
    "bananas": "2"
  }
}

Edit: Sorry I forgot to mention previously, I don't want a[0] b[0]

*"...a bit odd."* Inded. :-) `JSON.parse(JSON.stringify(x))` is almost **always** an anti-pattern. — T.J. Crowder, Apr 02 '21 at 11:38
I’m voting to close this question because it belongs to codereview.stackexchange.com — Alexandre Elshobokshy, Apr 02 '21 at 11:40
What is supposed to happen when `a` or `b` has more elements? — crashmstr, Apr 02 '21 at 11:45
@jabaa thanks. I was just wanting to know if es6 can make `[{}]` to be `{}` — olo, Apr 02 '21 at 11:49
Why didn't you ask this instead? What's the expected behavior if the array contains more elements, e.g. `const a = [{banana: '1'}, {apple: '2'}]`? — , Apr 02 '21 at 11:50
@crashmstr thanks! I only have two `a` `b` so didn't think much — olo, Apr 02 '21 at 11:50

Nina Scholz · Accepted Answer · 2021-04-02T11:47:04.023

1

You could get an object for each array and assign to the wanted properties.

const
    a = [{ apple: '1', banana: '2' }],
    b = [{ apples: '1', bananas: '2' }],
    result = { a: Object.assign({}, ...a), b: Object.assign({}, ...b) };

console.log(result);

edited Apr 02 '21 at 11:47

answered Apr 02 '21 at 11:40

Nina Scholz

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score 0 · Answer 2 · answered Apr 02 '21 at 11:40

0

You can achieve the same result with

const a = [{
  apple: '1',
  banana: '2',
}];

const b = [{
  apples: '1',
  bananas: '2',
}];

console.log({ a: a[0], b: b[0] })

answered Apr 02 '21 at 11:40

score 0 · Answer 3 · answered Apr 02 '21 at 11:40

If your current code is giving you the result you want, then you can just do this:

const result = {a, b};

Live Example:

const a = [
    {
      apple: '1',
      banana: '2',
    },
  ];

   const b = [
    {
      apples: '1',
      bananas: '2',
    },
];

const result = {a, b};
console.log(result);

If you want to make copies of the objects, you can do this:

const result = {
    a: a.map(o => ({...o})),
    b: b.map(o => ({...o})),
};

Live Example:

const a = [
    {
      apple: '1',
      banana: '2',
    },
  ];

   const b = [
    {
      apples: '1',
      bananas: '2',
    },
];

const result = {
    a: a.map(o => ({...o})),
    b: b.map(o => ({...o})),
};
console.log(result);

Or for a more generic deep copy operation, see this question's answers.

merge two array objects into one with its own key

3 Answers3