var baseFlatten = require('./_baseFlatten'),
baseIteratee = require('./_baseIteratee'),
baseRest = require('./_baseRest'),
baseUniq = require('./_baseUniq'),
isArrayLikeObject = require('./isArrayLikeObject'),
last = require('./last');
/**
* 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).
*
* @static
* @memberOf _
* @since 4.0.0
* @category Array
* @param {...Array} [arrays] The arrays to inspect.
* @param {Function} [iteratee=_.identity] The iteratee invoked per element.
* @returns {Array} Returns the new array of combined values.
* @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 }]
*/
var unionBy = baseRest(function(arrays) {
var iteratee = last(arrays);
if (isArrayLikeObject(iteratee)) {
iteratee = undefined;
}
return baseUniq(baseFlatten(arrays, 1, isArrayLikeObject, true), baseIteratee(iteratee, 2));
});
module.exports = unionBy;