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

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

'use strict';

Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });

const isArrayLike = require('../predicate/isArrayLike.js');

function flatten(value, depth = 1) {
    const result = [];
    const flooredDepth = Math.floor(depth);
    if (!isArrayLike.isArrayLike(value)) {
        return result;
    }
    const recursive = (arr, currentDepth) => {
        for (let i = 0; i < arr.length; i++) {
            const item = arr[i];
            if (currentDepth < flooredDepth &&
                (Array.isArray(item) ||
                    Boolean(item?.[Symbol.isConcatSpreadable]) ||
                    (item !== null && typeof item === 'object' && Object.prototype.toString.call(item) === '[object Arguments]'))) {
                if (Array.isArray(item)) {
                    recursive(item, currentDepth + 1);
                }
                else {
                    recursive(Array.from(item), currentDepth + 1);
                }
            }
            else {
                result.push(item);
            }
        }
    };
    recursive(Array.from(value), 0);
    return result;
}

exports.flatten = flatten;