Merging nested arrays to form 1-d array in JavaScript

Problem

We are required to write a JavaScript function that takes in two nested arrays, arr1 and arr2, as the first and the second argument.

Our function should create and return a third array that contains all the elements of arr1 and arr2 but flattened to single dimension

For example, if the input to the function is −

const arr1 = [    1, [       2, [          4, 5, [             6          ]       ]    ] ]; const arr2 = [    11, 12, [       16, 18, [          19, 21, [             23          ]       ]    ] ];

Then the output should be −

const output = [1, 2, 4, 5, 6, 11, 12, 16, 18, 19, 21, 23];

Example

Following is the code −

 Live Demo

const arr1 = [    1, [       2, [          4, 5, [             6          ]       ]    ] ]; const arr2 = [    11, 12, [       16, 18, [          19, 21, [             23          ]       ]    ] ]; const flattenAndMerge = (arr1 = [], arr2 = []) => {    const res = [];    const flatten = (arr = []) => {       for(let i = 0; i < arr.length; i++){          if(Array.isArray(arr[i])){             flatten(arr[i]);          }else if(typeof arr[i] === 'number'){             res.push(arr[i])          };       };    };    flatten(arr1);    flatten(arr2);    return res; }; console.log(flattenAndMerge(arr1, arr2));

Output

Following is the console output −

[    1, 2, 4, 5, 6,    11, 12, 16, 18, 19,    21, 23 ]