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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
- };
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