Array Flattening (Specified Depth)

/**
 * Array flattening with configurable depth
 * @param arr Array to be flattened
 * @param depth Flattening depth (Infinity by default)
 * @returns Flattened array
 */
function flattenArray<T>(arr: any[], depth = Infinity): T[] {
  return arr.reduce((acc, item) => {
    if (Array.isArray(item) && depth > 0) {
      acc.push(...flattenArray(item, depth - 1));
    } else {
      acc.push(item);
    }
    return acc;
  }, [] as T[]);
}

// Usage Example
console.log(flattenArray([1, [2, [3, [4]]]], 2)); // [1, 2, 3, [4]]
console.log(flattenArray([1, [2, [3]]])); // [1, 2, 3]