How to Create Nested Arrays from a Nest of Arrays in JavaScript ?

Creating nested arrays from a nest of arrays in JavaScript involves organizing multiple arrays into a hierarchical structure, which is often useful for managing and representing complex data relationships. This process entails encapsulating arrays within other arrays to form multi-dimensional structures. Such nested arrays can represent various data structures, from simple lists of lists to more intricate tree-like structures.

These are the following methods:

Method 1: Using map() method

This map method is used to iterate over the input arrays using map(), and for each array, creating a new array containing the original array as its only element. The push() method is then used to append each new array to a resulting array.

Example: Creating the nested array from the given in arrays using the map method.

Javascript

function createNestedArray(...arrays) {
    return arrays.map(array => [array]);
}

// Example usage:
const arr1 = [1, 2, 3];
const arr2 = ['a', 'b', 'c'];
const arr3 = [true, false];
const nestedArray = createNestedArray(arr1, arr2, arr3);
console.log(nestedArray);

Output

[ [ [ 1, 2, 3 ] ], [ [ 'a', 'b', 'c' ] ], [ [ true, false ] ] ]

Method 2: Using reduce() method

In this approch, reduce() is used to iterate over the input arrays. For each array, a new array containing the original array as its only element is created and appended to the accumulating result array using push().

Example: Creating the nested array from the given in arrays using the reduce method.

Javascript

function createNestedArray(...arrays) {
    return arrays.reduce((acc, curr) => {
        acc.push([curr]);
        return acc;
    }, []);
}

// Example usage:
const arr1 = [1, 2, 3];
const arr2 = ['a', 'b', 'c'];
const arr3 = [true, false];
const nestedArray = createNestedArray(arr1, arr2, arr3);
console.log(nestedArray);

Output

[ [ [ 1, 2, 3 ] ], [ [ 'a', 'b', 'c' ] ], [ [ true, false ] ] ]

Method 3: Using from() method

In this method, from() is utilised to create a new array from the input arrays. A mapping function passed to from() constructs new arrays, with each original array nested within another array. This method offers a concise way to create nested arrays from existing arrays.

Example: Creating the nested array from the given in arrays using the from method.

Javascript

function createNestedArray(...arrays) {
    return Array.from(arrays, array => [array]);
}

// Example usage:
const arr1 = [1, 2, 3];
const arr2 = ['a', 'b', 'c'];
const arr3 = [true, false];
const nestedArray = createNestedArray(arr1, arr2, arr3);
console.log(nestedArray);

Output

[ [ [ 1, 2, 3 ] ], [ [ 'a', 'b', 'c' ] ], [ [ true, false ] ] ]