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;