_.flatMap

_.flatMap(collection, [iteratee=_.identity])

Creates a flattened array of values by running each element in collection thru iteratee and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).

Since

4.0.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Function): The function invoked per iteration.

Returns

(Array): Returns the new flattened array.

Example

function duplicate(n) {
  return [n, n];
}
 
_.flatMap([1, 2], duplicate);
// => [1, 1, 2, 2]