es-toolkit/dist/fp/array/flatten.js

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

const require_flatten = require("../../array/flatten.js");
const require_lazy = require("../_internal/lazy.js");
//#region src/fp/array/flatten.ts
/**
* Creates a function that flattens an array up to the specified depth.
*
* The returned function is lazy-capable inside {@link pipe}. A trailing
* short-circuiting operator can stop before later nested values are visited.
*
* @template T - The type of elements in the array.
* @template D - The depth to which nested arrays should be flattened.
* @param depth - The flattening depth. Defaults to 1.
* @returns A function that maps the piped array to a flattened array.
*
* @example
* import { flatten, pipe } from 'es-toolkit/fp';
*
* pipe([1, [2, [3]]], flatten(2));
* // => [1, 2, 3]
*/
function flatten(depth = 1) {
	const flooredDepth = Math.floor(depth);
	function flattenEager(array) {
		return require_flatten.flatten(array, depth);
	}
	const flattenLazy = require_lazy.createLazyFunction((value, _index, emit) => {
		emitFlattened(value, 0, flooredDepth, emit);
	});
	return require_lazy.combineEagerAndLazyFunctions(flattenEager, flattenLazy);
}
function emitFlattened(value, currentDepth, maxDepth, emit) {
	if (Array.isArray(value) && currentDepth < maxDepth) {
		for (let index = 0; index < value.length; index++) emitFlattened(value[index], currentDepth + 1, maxDepth, emit);
		return;
	}
	emit(value);
}
//#endregion
exports.flatten = flatten;