Skip to main content

unionBy

_.unionBy(iteratee, arrays, arrays) # Ⓢ [Ⓣ][1] Ⓝ

This method is like _.union except that it accepts iteratee which is



invoked for each element of each arrays to generate the criterion by



which uniqueness is computed. Result values are chosen from the first



array in which the value occurs. The iteratee is invoked with one argument:



(value).

Since​

4.0.0

Arguments​

  1. iteratee (Function): The iteratee invoked per element.
  2. arrays (Array): The arrays to inspect.
  3. arrays (Array): The arrays to inspect.

Returns​

(Array): Returns the new array of combined values.

Example​

_.unionBy(Math.floor, [2.1], [1.2, 2.3]);
// => [2.1, 1.2]

// The `_.property` iteratee shorthand.
_.unionBy('x', [{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }]);
// => [{ 'x': 1 }, { 'x': 2 }]