@augment-vir/common/dist/augments/array/extract-duplicates.js

A collection of augments, helpers types, functions, and classes for any JavaScript environment.

import { check } from '@augment-vir/assert';
/**
 * Finds all duplicates.
 *
 * @category Array
 * @category Package : @augment-vir/common
 * @example
 *
 * ```ts
 * import {extractDuplicates} from '@augment-vir/common';
 *
 * const result = extractDuplicates([
 *     'a',
 *     'b',
 *     '',
 *     'a',
 * ]);
 * // result is `{duplicates: ['a'], uniques: ['b', '']}`
 * ```
 *
 * @package [`@augment-vir/common`](https://www.npmjs.com/package/@augment-vir/common)
 */
export function extractDuplicates(items, comparator = check.strictEquals) {
    const duplicates = [];
    const uniques = [];
    items.forEach((item) => {
        const duplicatesIndex = duplicates.findIndex((duplicateEntry) => comparator(duplicateEntry, item));
        if (duplicatesIndex < 0) {
            const uniquesIndex = uniques.findIndex((uniqueEntry) => comparator(uniqueEntry, item));
            if (uniquesIndex < 0) {
                uniques.push(item);
            }
            else {
                uniques.splice(uniquesIndex, 1);
                duplicates.push(item);
            }
        }
    });
    return {
        duplicates,
        uniques,
    };
}