es-toolkit/dist/set/reduce.mjs

A state-of-the-art, high-performance JavaScript utility library with a small bundle size and strong type annotations.

//#region src/set/reduce.ts
/**
* Reduces a Set to a single value by iterating through its elements and applying a callback function.
*
* This function iterates through all elements of the Set and applies the callback function to each element,
* accumulating the result. If an initial value is provided, it is used as the starting accumulator value.
* If no initial value is provided and the Set is empty, a TypeError is thrown.
*
* @template T - The type of elements in the Set.
* @template A - The type of the accumulator.
* @param set - The Set to reduce.
* @param callback - A function that processes each element and updates the accumulator.
* @param [initialValue] - The initial value for the accumulator. If not provided, the first element in the Set is used.
* @returns The final accumulated value.
* @throws {TypeError} If the Set is empty and no initial value is provided.
*
* @example
* const set = new Set([1, 2, 3]);
* const result = reduce(set, (acc, value) => acc + value, 0);
* // result will be: 6
*
* @example
* const set = new Set([10, 20]);
* const result = reduce(set, (acc, value) => acc + value);
* // result will be: 30 (starts with first value 10)
*/
function reduce(set, callback, initialValue) {
	if (initialValue == null && set.size === 0) throw new TypeError("Reduce of empty set with no initial value");
	let accumulator = initialValue;
	for (const value of set) if (accumulator == null) accumulator = value;
	else accumulator = callback(accumulator, value, value, set);
	return accumulator;
}
//#endregion
export { reduce };