How to sort an array of objects by custom order given as a string or array?

Question

Given array:

var someAnswers = [
  {
    answer:  'Lyndon Johnson', // answer A
    comment: '...'
  },
  {
    answer:  'Richard Nixon', // answer B
    comment: '...'
  },
  {
    answer:  'Jimmy Carter', // answer C
    comment: '...'
  },
  {
    answer:  'Gerald Ford', // answer D
    comment: '...'
  }
];

Some custom order:

customOrder = 'A, C, B, D';

or

customOrder = ['A', 'C', 'B', 'D'];

Do something like this:

someAnswers.sort(customOrder);

Desired result:

[
  {
    "answer": "Lyndon Johnson",
    "comment": "..."
  },
  {
    "answer": "Jimmy Carter",
    "comment": "..."
  },
  {
    "answer": "Richard Nixon",
    "comment": "..."
  },
  {
    "answer": "Gerald Ford",
    "comment": "..."
  }
]

Another custom order:

anotherCustomOrder = 'D, B, A, C';

or

anotherCustomOrder = ['D', 'B', 'A', 'C'];

Do something like this:

someAnswers.sort(anotherCustomOrder);

Desired result:

[
  {
    "answer": "Gerald Ford",
    "comment": "..."
  },
  {
    "answer": "Richard Nixon",
    "comment": "..."
  },
  {
    "answer": "Lyndon Johnson",
    "comment": "..."
  },
  {
    "answer": "Jimmy Carter",
    "comment": "..."
  }
]

This is most likely a duplicate of [How do I sort an array of objects based on the ordering of another array?](https://stackoverflow.com/questions/9755889/how-do-i-sort-an-array-of-objects-based-on-the-ordering-of-another-array) — Heretic Monkey, Oct 12 '21 at 20:17
Just because "Gerald Ford" is the fourth answer (and "D" is the fourth letter in the alphabet). — Ben, Oct 12 '21 at 20:25
Does this answer your question? [How do I sort an array of objects based on the ordering of another array?](https://stackoverflow.com/questions/9755889/how-do-i-sort-an-array-of-objects-based-on-the-ordering-of-another-array) — Heretic Monkey, Oct 12 '21 at 20:26

Paul · Answer 1 · 2021-10-13T04:49:14.647

    const sorting = (currentArray, indexArr) => {
        const reArrangedArr = [];
        const deepCopied = JSON.parse(JSON.stringify(currentArray));
        indexArr.forEach(index => reArrangedArr.push(deepCopied[index]));
        return reArrangedArr;
    }
    var someAnswers = [
      {
        answer:  'Lyndon Johnson', // answer A
        comment: '...'
      },
      {
        answer:  'Richard Nixon', // answer B
        comment: '...'
      },
      {
        answer:  'Jimmy Carter', // answer C
        comment: '...'
      },
      {
        answer:  'Gerald Ford', // answer D
        comment: '...'
      }
    ];
    console.log(sorting(someAnswers, [3,0,1,2]))

score 1 · Answer 2 · answered Oct 12 '21 at 20:13

1

If you were willing to replace the letters with numbers in customOrder, you could do something like this:

customOrder = [0, 2, 1, 3];

sort(someAnswers, customOrder) {
    res = [];
    customOrder.forEach((n) => {
        res.push(someAnswers[n]);
    }
    return res;
}

Alternatively, if you really want to use letters:

customOrder = ["A", "C", "B", "D"];

sort(someAnswers, customOrder) {
    res = [];
    customOrder.forEach((n) => {
        res.push(someAnswers[n.charCodeAt(0) - 65]);
    }
    return res;
}

answered Oct 12 '21 at 20:13

Anon Anonymous

33
6

Could you add a working snippet? – Ben Oct 12 '21 at 20:43
A working snippet would be appreciated. At least there is missing `);`. – Ben Oct 14 '21 at 14:52

Ele · Answer 3 · 2021-10-12T20:27:26.670

You can create an object with the indexes according to the desired order, and then use the function Array.prototype.map and extract the values by using the previously created indexes array.

const someAnswers = [  {    answer:  'Lyndon Johnson', comment: '...'  },  {    answer:  'Richard Nixon',    comment: '...'  },  {    answer:  'Jimmy Carter',     comment: '...'  },  {    answer:  'Gerald Ford',    comment: '...'  }],
      answerIndexes = ['A', 'B', 'C', 'D'].reduce((a, c, i) => ({...a, [c]: i}), {}),
      customOrder = ['A', 'C', 'B', 'D'],
      sorted = customOrder.map(L => someAnswers[answerIndexes[L]]);

console.log(sorted);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Thank you! Could you explain the part where the magic happens (`reduce((a, c, i) => ({...a, [c]: i}), {})`) and the `L` in `map()`? — Ben, Oct 15 '21 at 20:36

How to sort an array of objects by custom order given as a string or array?

3 Answers3