Get multiple highest values from array of objects

August 1, 2022

I’ve got an array of objects:

[
  {
    questionId: 1,
    delta: 3,
  },
  {
    questionId: 3,
    delta: 11,
  },
  {
    questionId: 6,
    delta: 11,
  }
  ....
]

With up to 43 entries.

To get the entry with the highest delta out of this, I would do something like

const maxDelta = Math.max.apply(Math, array.map(question=> {
    return question.delta;
}));

But now I need the 10 highest delta’s out of this array. How would I do that?

>Solution :

If the array were huge you’d probably look into a heap or selection-based algorithm, but as your array is tiny (with up to 43 elements), you can just sort it in descending order of delta:

const array = [{questionId: 1,delta: 3,},{questionId: 3,delta: 11,},{questionId: 6,delta: 11,},{questionId: 7,delta: 8,},{questionId: 8,delta: 6,},{questionId: 10,delta: 4,},{questionId: 12,delta: 7,},{questionId: 13,delta: 16,},{questionId: 16,delta: 2,},{questionId: 17,delta: 14,},{questionId: 18,delta: 12,},{questionId: 21,delta: 19,},{questionId: 23,delta: 5,}];
const result = array.sort((a, b) => b.delta - a.delta)
                    .slice(0, 10)
                    .map(a => a.delta);
console.log(result);