Remove duplicate objects from an array but merge nested objects

Question

Currently have an array of objects which contain game releases. However game releases can happen on multiple platforms and these appear as separate objects within the array. I'm looking to remove duplicate games by comparing the game id but merge the platforms object

I have tried using the reduce function which successfully removes duplicate objects by game id but I'm unable to adapt this to merge platforms

const filteredArr = data.reduce((acc, current) => {
  const x = acc.find(item => item.game.id === current.game.id);

  if (!x) {
    return acc.concat([current]);
  } else {
    return acc;
  }
}, []);

Current Array:

const data = [{
  "id": 157283,
  "date": 1553212800,
  "game": {
    "id": 76882,
    "name": "Sekiro: Shadows Die Twice",
    "popularity": 41.39190295640344
  },
  "human": "2019-Mar-22",
  "m": 3,
  "platform": {"id": 48, "name": "PlayStation 4"},
  "region": 8,
  "y": 2019
}, {
  "id": 12,
  "date": 1553212800,
  "game": {
    "id": 76832,
    "name": "Spiderman",
    "popularity": 41.39190295640344
  },
  "human": "2019-Mar-22",
  "m": 3,
  "platform": {"id": 6, "name": "PC (Microsoft Windows)"},
  "region": 8,
  "y": 2019
}, {
  "id": 157283,
  "date": 1553212800,
  "game": {
    "id": 76882,
    "name": "Sekiro: Shadows Die Twice",
    "popularity": 41.39190295640344
  },
  "human": "2019-Mar-22",
  "m": 3,
  "platform": {"id": 48, "name": "Xbox"},
  "region": 8,
  "y": 2019
}]

Expected format after merge:

[{
  "id": 157283,
  "date": 1553212800,
  "game": {
    "id": 76882,
    "name": "Sekiro: Shadows Die Twice",
    "popularity": 41.39190295640344
  },
  "human": "2019-Mar-22",
  "m": 3,
  "platforms": ["PlayStation", "Xbox"],
  "region": 8,
  "y": 2019
}, {
  "id": 12,
  "date": 1553212800,
  "game": {
    "id": 76832,
    "name": "Spiderman",
    "popularity": 41.39190295640344
  },
  "human": "2019-Mar-22",
  "m": 3,
  "platforms": ["Playstation"],
  "region": 8,
  "y": 2019
}]

Answer 1

You were really close, you just need to change the logic a bit. You can try something like the following; an example - https://repl.it/@EQuimper/ScaryBumpyCircle

const filteredArr = data.reduce((acc, current) => {
  const x = acc.find(item => item.game.id === current.game.id);

  if (!x) {
    current.platform = [current.platform]
    acc.push(current);
  } else {
    x.platform.push(current.platform);
  }

  return acc;
}, []);

The return value is

[
  {
    "id": 157283,
    "date": 1553212800,
    "game": {
      "id": 76882,
      "name": "Sekiro: Shadows Die Twice",
      "popularity": 41.39190295640344
    },
    "human": "2019-Mar-22",
    "m": 3,
    "platform": [
      {
        "id": 48,
        "name": "PlayStation 4"
      },
      {
        "id": 48,
        "name": "Xbox"
      }
    ],
    "region": 8,
    "y": 2019
  },
  {
    "id": 12,
    "date": 1553212800,
    "game": {
      "id": 76832,
      "name": "Spiderman",
      "popularity": 41.39190295640344
    },
    "human": "2019-Mar-22",
    "m": 3,
    "platform": [
      {
        "id": 6,
        "name": "PC (Microsoft Windows)"
      }
    ],
    "region": 8,
    "y": 2019
  }
]

If you want to have just an array of platform strings, go with

const filteredArr = data.reduce((acc, current) => {
  const x = acc.find(item => item.game.id === current.game.id);

  if (!x) {
    current.platform = [current.platform.name]
    acc.push(current);
  } else {
    x.platform.push(current.platform.name);
  }

  return acc;
}, []);

And now the return value is

[
  {
    "id": 157283,
    "date": 1553212800,
    "game": {
      "id": 76882,
      "name": "Sekiro: Shadows Die Twice",
      "popularity": 41.39190295640344
    },
    "human": "2019-Mar-22",
    "m": 3,
    "platform": [
      "PlayStation 4",
      "Xbox"
    ],
    "region": 8,
    "y": 2019
  },
  {
    "id": 12,
    "date": 1553212800,
    "game": {
      "id": 76832,
      "name": "Spiderman",
      "popularity": 41.39190295640344
    },
    "human": "2019-Mar-22",
    "m": 3,
    "platform": [
      "PC (Microsoft Windows)"
    ],
    "region": 8,
    "y": 2019
  }
]