4.17.11
3.10.1
2.4.2
1.3.1

_.unionBy([arrays], [iteratee=_.identity])

sourcenpm package

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

argument
[arrays]
[iteratee=_.identity]
type
...Array
Function
description
The arrays to inspect.
The iteratee invoked per element.

Returns

(array)

Example

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

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

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

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