How to return an array of objects with a key of least value? [duplicate]

Question

I have an array of objects like below. How to return an array of objects containing the minimum value of bidAmount?

[
{userId:2,bidAmount:9200},
{userId:3,bidAmount:8500},
{userId:4,bidAmount:8100},
{userId:5,bidAmount:8100}
]

Expected result:

[
{userId:4,bidAmount:8100},
{userId:5,bidAmount:8100}
]

I tried Array.reduce to find minimum but it returns only one object

var min = result.reduce(function(res, obj) {
    return (obj.bidAmount < res.bidAmount) ? obj : res;
});
//Returns {userId: 4, bidAmount: 8100}

How can this be achieved?

Endothermic_Dragon · Accepted Answer · 2021-05-23 17:25:24Z

1

You could reduce with an array as result set and check the bidAmount, if it is smaller or equal.

const data = [{userId: 2, bidAmount: 9200}, {userId: 3, bidAmount: 8500}, {userId: 4, bidAmount: 8100}, {userId: 5, bidAmount: 8100}]
var minima = data.reduce((acc, el, index) => {
  if (!index || acc[0].bidAmount > el.bidAmount) return [el];
  if (acc[0].bidAmount === el.bidAmount) acc.push(el);
  return acc;
}, null);

console.log(minima);

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

edited May 23, 2021 at 17:25

Endothermic_Dragon

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answered May 22, 2021 at 15:59

Nina Scholz

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Comments

Endothermic_Dragon · Accepted Answer · 2021-05-23 15:21:42Z

0

First, get all the bidAmounts in an array. After that, get the indexes of the smallest bidAmount (and store them in indexs). Finally, just get and return the elements by the indexs.

const data = [{userId:2,bidAmount:9200}, {userId:3,bidAmount:8500}, {userId:4,bidAmount:8100}, {userId:5,bidAmount:8100}];

var bidAmounts = data.map(el => el.bidAmount),
    minVal = Math.min(...bidAmounts),
    filteredData = data.filter(dataPoint => dataPoint.bidAmount == minVal);

console.log(filteredData)

edited May 23, 2021 at 15:21

answered May 22, 2021 at 16:09

Endothermic_Dragon

1,1776 silver badges13 bronze badges

5 Comments

adiga Over a year ago

You could calculate Math.min(...bidAmounts) before hand instead of doing that in every loop.

Endothermic_Dragon Over a year ago

I originally did that, but for some reason I removed it - I'm dumb 🙃. Thanks for catching it!

Ben Stephens Over a year ago

Is there a benefit to doing bidAmounts.forEach( ... ) versus just filtering the data using minVal at this point do you think?

Endothermic_Dragon Over a year ago

You cannot use filter and return indices. However, I was working on something very similar using reduce, and further lessened the code above using it (it was bothering me for a long time).

Ben Stephens Over a year ago

I was wondering if the indices were really necessary. Like maybe once you've got minVal, you could just do: data.filter((item) => item.bidAmount === minVal).

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