flattenDeep ​
Returns a new array with all depths of a nested array flattened.
typescript
const result = flattenDeep(arr);Reference ​
flattenDeep(arr) ​
Use flattenDeep when you want to completely flatten a nested array, no matter how deeply nested it is. It unwinds all nested arrays within the array, creating a single flat structure.
It works identically to calling Array#flat as flat(Infinity) in the JavaScript language, but it's faster.
typescript
import { flattenDeep } from 'es-toolkit/array';
// Flatten all nested levels
const array = [1, [2, [3]], [4, [5, 6]]];
const result = flattenDeep(array);
// Returns: [1, 2, 3, 4, 5, 6]It completely flattens even highly complex nested structures.
typescript
import { flattenDeep } from 'es-toolkit/array';
const complexArray = [1, [2, [3, [4, [5]]]], 6];
const result = flattenDeep(complexArray);
// Returns: [1, 2, 3, 4, 5, 6]Parameters ​
arr(T[]): The nested array to flatten.
Returns ​
(Array<ExtractNestedArrayType<T>>): Returns a new array with all depths flattened.