lodash: Get duplicate values from an array

Question

Say I have an array like this: [1, 1, 2, 2, 3]

I want to get the duplicates which are in this case: [1, 2]

Does lodash support thi

Answer 1

Well you can use this piece of code which is much faster as it has a complexity of O(n) and this doesn't use Lodash.

[1, 1, 2, 2, 3]
.reduce((agg,col) => {
  agg.filter[col] = agg.filter[col]? agg.dup.push(col): 2;
  return agg
 },
 {filter:{},dup:[]})
.dup;

//result:[1,2]