How to sort an array of objects based on another?

Question

I have these arrays:

Array 1:

const arr1 = [
  {_id: "13", qtde: 1, color: "red", size: "100x100"},
  {_id: "16", qtde: 5, color: "green", size: "200x200"},
  {_id: "1", qtde: 3, color: "yellow", size: "300x300"},
  {_id: "23", qtde: 2, color: "purple", size: "500x500"},
  {_id: "3", qtde: 0, color: "orange", size: "200x200"}
]

Array 2:

const arr2 = [
  {_id: "23", name: "Produto-23", price: "48.99"},
  {_id: "13", name: "Produto-13", price: "58.99"},
  {_id: "3", name: "Produto-3", price: "58.99"},
  {_id: "1", name: "Produto-1", price: "58.99"},
  {_id: "16", name: "Produto-16", price: "58.99"}
]

Expected Output:

const arr2 = [
  {_id: "13", name: "Produto-13", price: "58.99"},
  {_id: "16", name: "Produto-16", price: "58.99"},
  {_id: "1", name: "Produto-1", price: "58.99"},
  {_id: "23", name: "Produto-23", price: "48.99"},
  {_id: "3", name: "Produto-3", price: "58.99"}
]

As can be seen they are different but they have the property _id in common, but not in the same order. What I want to do is reorganize the second array to have the same order as the first one based on its property _id .

Just to be clear, I don't want to merge the arrays or change anything besides the order of the second one.

I thought about using Array.sort , but since I don't have a property of reference I don't know how it could be applied here. The basic idea is to use the index of the first array as reference, since it won't change, but I don't know how as well.

How could I do that?

Answer 1

You can use .findIndex in the sort as follows:

 const arr1 = [ {_id: "13", qtde: 1, color: "red", size: "100x100"}, {_id: "16", qtde: 5, color: "green", size: "200x200"}, {_id: "1", qtde: 3, color: "yellow", size: "300x300"}, {_id: "23", qtde: 2, color: "purple", size: "500x500"}, {_id: "3", qtde: 0, color: "orange", size: "200x200"} ] const arr2 = [ {_id: "23", name: "Produto-23", price: "48.99"}, {_id: "13", name: "Produto-13", price: "58.99"}, {_id: "3", name: "Produto-3", price: "58.99"}, {_id: "1", name: "Produto-1", price: "58.99"}, {_id: "16", name: "Produto-16", price: "58.99"} ] const arr2Sorted = arr2.sort((a,b) => { const indexOfA = arr1.findIndex(e => e._id === a._id); const indexOfB = arr1.findIndex(e => e._id === b._id); return indexOfA - indexOfB; }); console.log(arr2Sorted);

Answer 2

You need to create a lookup map from the first array and then sort the other array with the lookup map.

 const createLookup = (arr, key) => arr.reduce((acc, curr, index) => ({...acc, [curr[key]]: index }), {}); const sortWithLookup = (arr, key, lookup) => arr.sort((a, b) => lookup[a[key]] - lookup[b[key]]); const arr1 = [ { _id: "13", qtde: 1, color: "red", size: "100x100" }, { _id: "16", qtde: 5, color: "green", size: "200x200" }, { _id: "1", qtde: 3, color: "yellow", size: "300x300" }, { _id: "23", qtde: 2, color: "purple", size: "500x500" }, { _id: "3", qtde: 0, color: "orange", size: "200x200" } ]; const arr2 = [ { _id: "23", name: "Produto-23", price: "48.99" }, { _id: "13", name: "Produto-13", price: "58.99" }, { _id: "3", name: "Produto-3", price: "58.99" }, { _id: "1", name: "Produto-1", price: "58.99" }, { _id: "16", name: "Produto-16", price: "58.99" } ]; const lookup = createLookup(arr1, '_id'); const sorted = sortWithLookup(arr2, '_id', lookup); sorted.forEach(item => console.log(JSON.stringify(item)));

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