javascript - pick unique items from first array

Question

Suppose I have two arrays of objects

const array1 =  [{
        listName: 'My top 5 Sci-Fi Movies',
        listCreator: 'Anon',
        listItem: 'The Fifth Element'
      },
      {
        listName: 'My top 5 Sci-Fi Movies',
        listCreator: 'Anon',
        listItem: 'Cube'
      }]

and

const array2 = [{
        listName: 'My top 5 Sci-Fi Movies',
        listCreator: 'Anon',
        listItem: 'The Fifth Element'
      },
      {
        listName: 'My top 5 Sci-Fi Movies',
        listCreator: 'Dude',
        listItem: 'Cube'
      }]

I want to able to compare the two arrays and create a new array that only has unique members of array1, in this case

const uniqueArray = [{
            listName: 'My top 5 Sci-Fi Movies',
            listCreator: 'Anon',
            listItem: 'Cube'
          }]

I am using lodash library (but not necessary to solve this problem if not required) and I'd like to accomplish this in the fewest lines of code possible.

Thanks for sharing your inputs and expected output. Can you share what you've tried? — stealththeninja, Jul 25 '20 at 02:29
I had tried _.uniq, _.uniWith (used with _.isEqual) Set. I'm sorry I don't have details. I just learning JS and had been at this for a couple of days trying different things. — Kamal, Jul 25 '20 at 21:39

score 1 · Answer 1 · answered Jul 25 '20 at 21:58

hello dear brother you use Hashset to fetch automatically Unique Data from list

HashSet<Integer>set = new HashSet<Integer>(list1);
List<Integer>list2 = new ArrayList<Integer>(set);

and then pass this Hashset to List again

ITS JAVA CODE BUT LOGIC IS SAME FOR EVERY LANGUAGE

score 0 · Accepted Answer · answered Jul 25 '20 at 21:43

After banging my head around the intertubes, I found a simple and elegant solution.

If I (using lodash) do

const arrNew = _.differenceWith(array1, array2, _.isEqual);

arrNew is a new array of unique items from array1. Hope this helps someone else out. Would love to see if there's another more performant solution.

https://lodash.com/docs/4.17.15#differenceWith

javascript - pick unique items from first array

2 Answers2