54 lines
1.7 KiB
JavaScript
54 lines
1.7 KiB
JavaScript
const require_identity = require("../../function/identity.js");
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const require_range = require("../../math/range.js");
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const require_isArrayLike = require("../predicate/isArrayLike.js");
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//#region src/compat/array/reduce.ts
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/**
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* Reduces a collection to a single value using an iteratee function.
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*
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* @param collection - The collection to iterate over.
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* @param iteratee - The function invoked per iteration or the key to reduce over.
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* @param initialValue - The initial value.
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* @returns 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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* reduce(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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* reduce(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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* reduce(obj, (acc, value) => acc + value, 0); // => 6
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*/
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function reduce(collection, iteratee = require_identity.identity, accumulator) {
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const hasAccumulator = arguments.length >= 3;
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if (!collection) return accumulator;
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let keys;
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let startIndex = 0;
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if (require_isArrayLike.isArrayLike(collection)) {
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keys = require_range.range(0, collection.length);
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if (!hasAccumulator && collection.length > 0) {
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accumulator = collection[0];
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startIndex += 1;
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}
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} else {
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keys = Object.keys(collection);
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if (!hasAccumulator && keys.length > 0) {
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accumulator = collection[keys[0]];
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startIndex += 1;
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}
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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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exports.reduce = reduce;
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