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? — Heretic Monkey
– Heretic Monkey, Commented Oct 12, 2021 at 20:17
Just because "Gerald Ford" is the fourth answer (and "D" is the fourth letter in the alphabet). — Ben
– Ben, Commented Oct 12, 2021 at 20:25
Does this answer your question? How do I sort an array of objects based on the ordering of another array? — Heretic Monkey
– Heretic Monkey, Commented Oct 12, 2021 at 20:26

Anon Anonymous · Accepted Answer · 2021-10-12 20:13:24Z

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, 2021 at 20:13

Anon Anonymous

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2 Comments

Ben Over a year ago

Could you add a working snippet?

Ben Over a year ago

A working snippet would be appreciated. At least there is missing );.

Ele · Accepted Answer · 2021-10-12 20:27:26Z

1

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; }

edited Oct 12, 2021 at 20:27

answered Oct 12, 2021 at 20:20

Ele

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1 Comment

Ben Over a year ago

Thank you! Could you explain the part where the magic happens (reduce((a, c, i) => ({...a, [c]: i}), {})) and the L in map()?

Paul · Accepted Answer · 2021-10-13 04:49:14Z

1

    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]))

edited Oct 13, 2021 at 4:49

answered Oct 12, 2021 at 20:08

Paul

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