I'm looking for reduce elements of array to one object by same key (id).
I try to use Array.reduce, but cannot reduce same id elements.
Actually I don't really full understand Array.reduce's mechanism... :(
Can anybody help me?

const arr = [{id: 1, value: 1, key: 'email'}, {id: 1, value: 1, key: 'status'}, {id: 2, value: 2, key: 'email'}, {id: 2, value: 2, key: 'status'}];

// EXPECTED
const arr = [{id: 1, data: {'email': 1, 'status': 1}}, {id: 2, data: {'email': 2, 'status': 2}}];

// WHAT I DO
const result = arr.reduce((acc, cur)=>{
  const {id, key, value} = cur;
  acc.forEach(el => {
    if (el.id === id) {
      el.data[key] = value;
    }
  })
  acc = [...acc, {'id': id, 'data': { [key]: value }}];
  
  return acc
}, [])

// WHAT I GET
[
  { id: 1, data: { email: 1, status: 1 } },
  { id: 1, data: { status: 1 } },
  { id: 2, data: { email: 2, status: 2 } },
  { id: 2, data: { status: 2 } }
]

CodePudding user response：

You can use Array.prototype.reduce() this way,
By group them by id as an object and then use Object.values() to get the array that you wanted:

const arr = [
  {id: 1, value: 1, key: 'email'},
  {id: 1, value: 1, key: 'status'},
  {id: 2, value: 2, key: 'email'},
  {id: 2, value: 2, key: 'status'}
];

const arr2 = [
  {id: 1, data: {'email': 1, 'status': 1}},
  {id: 2, data: {'email': 2, 'status': 2}}
];

const res = Object.values(arr.reduce((acc, curr) => {
  if(!acc[curr.id]) {
    acc[curr.id] = {
      id: curr.id,
      data: {
        [curr.key]: curr.value
      }
    }
  } else {
    acc[curr.id].data = {
      ...acc[curr.id].data,
      [curr.key]: curr.value
    }
  }

  return acc;
}, {}));

console.log(res);

CodePudding user response：

Try this one

const arr = [{id: 1, value: 1, key: 'email'}, {id: 1, value: 1, key: 'status'}, {id: 2, value: 2, key: 'email'}, {id: 2, value: 2, key: 'status'}];

const result = arr.reduce((acc, {id, key, value}) => {
  const entry = acc.find(i => i.id === id);
  if (!entry) {
    acc.push({
      id, data: {
        [key]: value
      }
    });
  } else {
    entry.data[key] = value;
  }
  return acc;
}, []);

console.log(result);