Javascript : filter two array of object by id and return specific value-CodePudding

I'm trying to filter these two arrays of objects by their id (id & userId).

I want to return only the title where id and userId are equals

Thank you !

const usersData = [
  {
    "id": 1,
    "name": "Leanne Graham",
    "username": "Bret",
    "email": "[email protected]",
  }
]

const albumsData = [
  {
    "userId": 1,
    "id": 1,
    "title": "FooBar"
  },
  {
    "userId": 1,
    "id": 2,
    "title": "Trolololo"
  },
  {
    "userId": 3,
    "id": 3,
    "title": "omnis laborum odio"
  },
  {
    "userId": 4,
    "id": 4,
    "title": "non esse culpa molestiae omnis sed optio"
  }
]

const results = usersData.map(({ id }) =>
    albumsData.filter(({ userId }) => id === userId)
  );

console.log(results);

CodePudding user response：

Your code seems fine, but will return a nested array, so just use flatMap instead of map. And if you just want the title, just chain another .map to it:

const usersData = [{"id": 1,"name": "Leanne Graham","username": "Bret","email": "[email protected]",}];
const albumsData = [{"userId": 1,"id": 1,"title": "FooBar"},{"userId": 1,"id": 2,"title": "Trolololo"},{"userId": 3,"id": 3,"title": "omnis laborum odio"},{"userId": 4,"id": 4,"title": "non esse culpa molestiae omnis sed optio"}];

const results = usersData.flatMap(({ id }) =>
    albumsData.filter(({ userId }) => id === userId)
).map(({title}) => title);

console.log(results);

CodePudding user response：

const result = albumData.filter((data) => data.userId === usersData[0].id);

CodePudding user response：

As has been pointed out, you'll get a nested array using map. But that might actually be desired if you add another item to the usersData array as you'll get the results grouped by index. If not, use flatMap with another map on the end to get the title.

const results = usersData.flatMap(({ id }) =>
    albumsData.filter(({ userId }) => id === userId)
  ).map(entry=>entry.title)

Yields:

["FooBar","Trolololo"]

CodePudding user response：

Perhaps you just want the title values? In that case you code is find but just get the titles from that i.e.: Probably not the super most efficient but the verbose part at the end will show you what is going on there perhaps.

const usersData = [{
  "id": 1,
  "name": "Leanne Graham",
  "username": "Bret",
  "email": "[email protected]",
}];

const albumsData = [{
    "userId": 1,
    "id": 1,
    "title": "FooBar"
  },
  {
    "userId": 1,
    "id": 2,
    "title": "Trolololo"
  },
  {
    "userId": 3,
    "id": 3,
    "title": "omnis laborum odio"
  },
  {
    "userId": 4,
    "id": 4,
    "title": "non esse culpa molestiae omnis sed optio"
  }
];

const results = usersData.map(({
    id
  }) =>
  albumsData.filter(({
    userId
  }) => id === userId)
);
console.log(results);
// an array of titles
var titles = results[0].map((el) => {return el.title;});
console.log(titles);