reduce (Lodash Compatibility)

Use Array.prototype.reduce or Object.values with reduce

This reduce function operates slowly due to complex type handling and support for various input formats.

Instead, use the faster and more modern Array.prototype.reduce method, or for objects, use it together with Object.values.

Reduces an array or object to a single value.

const result = reduce(collection, iteratee, initialValue);

Reference

reduce(collection, iteratee, initialValue)

Iterates through all elements of an array or object to calculate an accumulated value. If an initial value is provided, it starts with that value; otherwise, it starts with the first element.

import { reduce } from 'es-toolkit/compat';

// Calculate sum of array
const numbers = [1, 2, 3, 4];
const sum = reduce(numbers, (acc, value) => acc + value, 0);
console.log(sum); // 10

// Calculate sum of object values
const scores = { math: 95, english: 87, science: 92 };
const totalScore = reduce(scores, (acc, value) => acc + value, 0);
console.log(totalScore); // 274

If no initial value is provided, the first element becomes the initial value and iteration starts from the second element.

import { reduce } from 'es-toolkit/compat';

const numbers = [1, 2, 3, 4];
const sum = reduce(numbers, (acc, value) => acc + value);
console.log(sum); // 10 (1 + 2 + 3 + 4)

// Empty array returns undefined
const empty = [];
const result = reduce(empty, (acc, value) => acc + value);
console.log(result); // undefined

Parameters

• collection (T[] | ArrayLike<T> | Record<string, T> | null | undefined): The array or object to iterate over.
• iteratee ((accumulator: any, value: any, index: PropertyKey, collection: any) => any): The function to call for each element. It receives the accumulated value, current value, index/key, and the original array/object.
• initialValue (any, optional): The initial value for the accumulator. If not provided, the first element becomes the initial value.

Returns

(any): Returns the final accumulated value after processing all elements.