javascript - Lodash union of arrays of objects

Question

I'd like to use the _.union function to create a union of two arrays of objects. Union works with arrays of primitives only as it uses === to examine if two values are equal.

I'd like to compare objects using a key property: objects with the same key property would be regarded equal. Is there a nice functional way to achieve that ideally using lodash?

Answer 1

A non pure lodash way to do this but using the array.concat function you are able to do this pretty simply along uniq():

var objUnion = function(array1, array2, matcher) {
  var concated = array1.concat(array2)
  return _.uniq(concated, false, matcher);
}

An alternative approach would be to use flatten() and uniq():

var union = _.uniq(_.flatten([array1, array2]), matcherFn);