54 lines
1.9 KiB
JavaScript
54 lines
1.9 KiB
JavaScript
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import { identity } from "../../function/identity.mjs";
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import { range } from "../../math/range.mjs";
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import { isArrayLike } from "../predicate/isArrayLike.mjs";
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//#region src/compat/array/reduceRight.ts
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/**
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* Reduces a collection to a single value using an iteratee function, starting from the right.
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*
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* @param {T[] | ArrayLike<T> | Record<string, T> | null | undefined} collection - The collection to iterate over.
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* @param {((accumulator: any, value: any, index: PropertyKey, collection: any) => any) | PropertyKey | object} iteratee - The function invoked per iteration or the key to reduce over.
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* @param {any} initialValue - The initial value.
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* @returns {any} - Returns the accumulated value.
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*
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* @example
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* // Using a reducer function
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* const array = [1, 2, 3];
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* reduceRight(array, (acc, value) => acc + value, 0); // => 6
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*
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* @example
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* // Using a reducer function with initialValue
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* const array = [1, 2, 3];
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* reduceRight(array, (acc, value) => acc + value % 2 === 0, true); // => false
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*
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* @example
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* // Using an object as the collection
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* const obj = { a: 1, b: 2, c: 3 };
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* reduceRight(obj, (acc, value) => acc + value, 0); // => 6
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*/
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function reduceRight(collection, iteratee = identity, accumulator) {
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if (!collection) return accumulator;
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let keys;
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let startIndex;
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if (isArrayLike(collection)) {
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keys = range(0, collection.length).reverse();
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if (accumulator == null && collection.length > 0) {
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accumulator = collection[collection.length - 1];
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startIndex = 1;
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} else startIndex = 0;
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} else {
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keys = Object.keys(collection).reverse();
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if (accumulator == null) {
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accumulator = collection[keys[0]];
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startIndex = 1;
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} else startIndex = 0;
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}
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for (let i = startIndex; i < keys.length; i++) {
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const key = keys[i];
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const value = collection[key];
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accumulator = iteratee(accumulator, value, key, collection);
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}
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return accumulator;
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}
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//#endregion
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export { reduceRight };
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