How to merge array of objects by its key in javascript

Question

I have a array of objects like these:

[
  {
    user: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user: {
      key2: ['3', '4', '5'],
    },
  },
  {
    user2: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user2: {
      key2: ['3', '4', '5'],
    },
  },
....
];

And I need to filter those by its keys and expecting an output like these

[
    {
        user: {
            key1: ['1', '2', '3'],
            key2: ['3', '4', '5'],
        },
    },
    {
        user2: {
            key1: ['1', '2', '3'],
            key2: ['3', '4', '5'],
            ....
        }
    }
]

Here user, user2 can be any key(userName) also key1, key 2 etc... may be any key(userActivity) with an array of string.

Here is the type of object:

[key: string]: {
    [key: string]: string[];
  };
}[];

Which will be the best way to filter this any help would be appreciated

do every object in the original array have only one key like user,user2or there could be more than one? — Alan Omar
– Alan Omar, Commented Apr 13, 2022 at 9:28

NeNaD · Accepted Answer · 2022-04-13 09:36:23Z

2

You can do it with reduce() method:

Iterate over each item from the data array
Check if the key from item already exists in final result
If it exists, concatenate current value and new value
If it does not exist, initialize new value

const data = [
 { user: { key1: ['1', '2', '3'] } },
 { user: { key2: ['3', '4', '5'] } },
 { user2: { key1: ['1', '2', '3'] } },
 { user2: { key2: ['3', '4', '5'] } }
];

const result = data.reduce((accumulator, currentValue)=>{
  const currentKey = Object.keys(currentValue)[0];
  
  if(Object.keys(accumulator).includes(currentKey)) {
     accumulator[currentKey] = {...accumulator[currentKey], ...currentValue[currentKey]};
  } else {
     accumulator[currentKey] = currentValue[currentKey];
  }
  
  return accumulator;
},{})

console.log(result);

edited Apr 13, 2022 at 9:36

answered Apr 13, 2022 at 9:30

NeNaD

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Comments

jeremy-denis · Accepted Answer · 2022-04-13 09:29:05Z

1

an idea with array.reduce

var data = [{
    user: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user: {
      key2: ['3', '4', '5'],
    },
  },
  {
    user2: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user2: {
      key2: ['3', '4', '5'],
    },
  }
];

let result = data.reduce((acc, curr) => {
  Object.keys(curr).forEach(key => {
    let found = acc.find(elem => elem[key]);
    if (found) {
      found[key] = {...found[key], ...curr[key]}
    } else {
      acc.push(curr);
    }
  });
  return acc;
}, []);

console.log(result);

answered Apr 13, 2022 at 9:29

jeremy-denis

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Comments

GeorgeK · Accepted Answer · 2022-04-13 09:51:11Z

0

Something like this perhaps

const initial = [
  {
    user: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user: {
      key2: ['3', '4', '5'],
    },
  },
  {
    user2: {
      key1: ['1', '2', '3'],
    },
  },
  {
    user2: {
      key2: ['3', '4', '5'],
    },
  },
];

let result = initial.reduce((acc, curr)=>{
    if(Object.keys(curr)[0]) {
        const key =Object.keys(curr)[0]
        const values = curr[key]
        acc = {
            ...acc,
            [key]: {
                ...acc[key],
                ...values
            }
        }
        return acc
    }
},[])

answered Apr 13, 2022 at 9:51

GeorgeK

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