To get duplicate values from an array with JavaScript Lodash, we can use the filter and includes methods.

For instance, we write

const dups = _.filter(arr, (val, i, iteratee) =>
  _.includes(iteratee, val, i + 1)
);

to call filter with arr and a callback that calls includes to check if val is included in the arr array itself from index i + 1 and oin.

iteratee is the arr array.

An array with the duplicates is returned.