TypeScript Array flat() Method

TypeScript flat() method of Arrays allows you to create an array while preserving the one.

It combines all the elements from sub-arrays, adds them to the parent array, to the specified depth, and enables you to merge a sub-array into its parent array without modifying the structure.

Syntax:

array.flat([depth]);

Parameters:

• depth (optional): The depth level specifies how deep a nested array structure should be flattened. It Defaults to 1.

Return Value:

• Flat() method returns a new array with its sub-array elements that are concatenated into it.

Example 1: In this example we will flat a single-level nested array.

Javascript

// This is a nested array
const nestedArray: number[][] =
    [[1, 2, 3], [4, 5], [6]];
// Here we are falttening nested array
const flattenedArray: number[] =
    nestedArray.flat();

console.log(flattenedArray);

Output:

[1, 2, 3, 4, 5, 6]

Example 2: In this example, we will flat a multi-level nested array.

Javascript

// This is a nested array
const deeplyNestedArray: number[][][] =
    [[1, [2, 3]], [[4], 5, [6]]];
// Here we are falttening nested array
const flattenedDeepArray: number[] =
    deeplyNestedArray.flat(2);

console.log(flattenedDeepArray);

Output:

[1, 2, 3, 4, 5, 6]