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| 'use strict';
|
| /**
| * Concat and flattens non-null values.
| * Ex: concat(1, undefined, 2, [3, 4]) = [1, 2, 3, 4]
| */
| function concat() {
| const args = Array.from(arguments).filter(e => e != null);
| const baseArray = Array.isArray(args[0]) ? args[0] : [args[0]];
| return Array.prototype.concat.apply(baseArray, args.slice(1));
| }
|
| /**
| * Dedupes array based on criterion returned from iteratee function.
| * Ex: uniqueBy(
| * [{ id: 1 }, { id: 1 }, { id: 2 }],
| * val => val.id
| * ) = [{ id: 1 }, { id: 2 }]
| */
| function uniqueBy(arr, fun) {
| const seen = {};
| return arr.filter(el => {
| const e = fun(el);
| return !(e in seen) && (seen[e] = 1);
| })
| }
|
| module.exports = {
| concat: concat,
| uniqueBy: uniqueBy
| };
|
|
