Concatenate objects inside an array of multiple array in js

Question

I want to convert an array from this:

const categories = [{
  name: 'category1',
  items: [
    {itemId: 1, name: 'Item1'},
    {itemId: 2, name: 'Item2'},
  ],
}, {
  name: 'category2',
  items: [
    {itemId: 3, name: 'Item3'},
    {itemId: 4, name: 'Item4'},
  ],
}];

to look something like this:

const result = [ 
  { itemId: 1, name: 'Item1' }, 
  { itemId: 2, name: 'Item2' }, 
  { itemId: 3, name: 'Item3' }, 
  { itemId: 4, name: 'Item4' },
];

Any helps would be amazing! Thank you.

Does this answer your question? How to map an Array of arrays to object like property and value? — Vectrobyte
– Vectrobyte, Commented Jan 25, 2020 at 3:46
This question is liable to downvotes as it is a very localized duplicate of another question. — Ṃųỻịgǻňạcểơửṩ
– Ṃųỻịgǻňạcểơửṩ, Commented Jan 25, 2020 at 5:57

Felipe Malara · Accepted Answer · 2020-01-25 03:54:24Z

1

If you're in a environment that supports nodejs over 11.0.0

You can use this piece of code:

categories.flatMap(({items}) => items)

Check the compatibility here

But if you're not in this kind of environment you could use this piece of code:

const result = []
const categories = [ { name: "category1"
        , items: 
          [ { itemId: 1, name: "Item1" } 
          , { itemId: 2, name: "Item2" } 
          ] 
        } 
      , { name: "category2"
        , items: 
          [ { itemId: 3, name: "Item3" } 
          , { itemId: 4, name: "Item4" } 
      ] } ]
categories.map(({items}) => items).forEach(arr => result.push(...arr))

answered Jan 25, 2020 at 3:54

Felipe Malara

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Comments

prabhatojha · Accepted Answer · 2020-01-25 03:22:04Z

0

Try this.

categories.reduce((result, item) => {
  result.push(...item.items);
  return result;
}, []);

answered Jan 25, 2020 at 3:22

prabhatojha

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