unionBy source npm

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

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. The iteratee is invoked with one argument: (value).

Arguments

  1. [arrays] (...Array)

    The arrays to inspect.

  2. [iteratee=_.identity] (Function|Object|string)

    The function invoked per element.

Returns (Array)

Returns the new array of combined values.

Example

_.unionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// => [2.1, 1.2, 4.3]

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