assign incremental index to nested array of object?

user_19637481 0
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How to assign incremental index to nested array of object below? each members will have a property 1,2,3,4

groupMembersByTitle = [{
    members: [{
        id: 'uuid'
    }, {
        id: 'uuid'
    }]
}, {
    members: [{
        id: 'uuid'
    }, {
        id: 'uuid'
    }]
}]

I'm stuck here

const r = groupMembersByTitle.map(o => ({
    ...o,
    members: o.members.map((o2, index) => ({
        ...o2,
        no: ++index
    }))
}))
javascript
4 Answers

You'll need a more persistent outer variable.

const groupMembersByTitle = [{
    members: [{
        id: 'uuid'
    }, {
        id: 'uuid'
    }]
}, {
    members: [{
        id: 'uuid'
    }, {
        id: 'uuid'
    }]
}];

let no = 1;
const mapped = groupMembersByTitle.map(
  obj => ({
    members: obj.members.map(
      member => ({ ...member, no: no++ })
    )
  })
);
console.log(mapped);

user_95152070

You can use the map parameter thisArg.

map(function(element, index, array) { /* … */ }, thisArg)


const groupMembersByTitle = [{
  members: [{ id: 'uuid' }, { id: 'uuid' }]
}, {
  members: [{ id: 'uuid' }, { id: 'uuid' }]
}];

const r = groupMembersByTitle.map(function(o1) {
  return ({
    members: o1.members.map(
      o2 => ({
        ...o2,
        no: ++this.acc
      })
    )
  });
}, { acc: 0 });

console.log(r);

user_127096130

You can do it using Array.prototype.map twice and use the indices of the arrays to calculate the no.

const 
  data = [
    { members: [{ id: "uuid" }, { id: "uuid" }] },
    { members: [{ id: "uuid" }, { id: "uuid" }] },
  ],
  result = data.map(({ members }, i) =>
    members.map((m, j) => ({
      ...m,
      no: i * (i ? data[i - 1].members.length : 1) + j + 1,
    }))
  );

console.log(result);

user_190956300 

function recursiveFunction(data, index) {
    if(Array.isArray(data)) {
      return data.reduce((acc, el) => this.recursiveFunction(el, acc), index);
    } else if(data.members) {
      return this.recursiveFunction(data.members, index);
    } else {
      data.no = index;
      return index + 1;
    }
  }

const groupMembersByTitle = [
  {
    members: [
      {
        id: 'uuid'
      },
      {
        id: 'uuid'
      }
    ]
  },
  {
    members: [
      {
        id: 'uuid'
      },
      {
        id: 'uuid'
      }
    ]
  }];


const res = recursiveFunction(groupMembersByTitle, 0);
console.log(groupMembersByTitle);
console.log(res);

user_108059890
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