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