Get list of duplicate objects in an array of objects

Question

I am trying to get duplicate objects within an array of objects. Let\'s say the object is like below.

values = [
  { id: 10, name: \'someName1\' },
  { id: 1         


        

Answer 1

Let's say you have:

arr = [
    { id:10, name: 'someName1' },
    { id:10, name: 'someName2' },
    { id:11, name: 'someName3' },
    { id:12, name: 'someName4' }
]

So, to get unique items:

unique = arr
     .map(e => e['id'])
     .map((e, i, final) => final.indexOf(e) === i && i)
     .filter(obj=> arr[obj])
     .map(e => arr[e]);

Then, result will be

unique = [
     { id:10, name: 'someName1' },
     { id:11, name: 'someName3' },
     { id:12, name: 'someName4' }
]

And, to get duplicate ids:

duplicateIds = arr
     .map(e => e['id'])
     .map((e, i, final) => final.indexOf(e) !== i && i)
     .filter(obj=> arr[obj])
     .map(e => arr[e]["id"])

List of IDs will be

duplicateIds = [10]

Thus, to get duplicates objects:

duplicate = arr.filter(obj=> dublicateIds.includes(obj.id));

Now you have it:

duplicate = [
    { id:10, name: 'someName1' },
    { id:10, name: 'someName2' }
]

Thanks https://reactgo.com/removeduplicateobjects/