How to Define Multidimensional Array in JavaScript?

In JavaScript, creating a multidimensional array involves nesting arrays within other arrays. Although JavaScript doesn’t directly provide built-in multidimensional arrays, we can simulate them by using arrays inside another array. Let’s explore a couple of ways to define and work with multidimensional arrays:

1. Array Literals:

   • The easiest way to define a multidimensional array is to use the array literal notation.
   • To declare an empty multidimensional array, you can use the same syntax as declaring a one-dimensional array:JavaScript

      

     let activities = []; // Empty multidimensional array
     
     

   • For example, you can create a two-tier array like this:JavaScript

      

     const matrix = [
       [1, 2, 3],
       [4, 5, 6]
     ];
     In the matrix array, we have two inner arrays, each containing three elements
     

2. Defining Arrays Inside Another Array:

   • You can manually create a multidimensional array by defining arrays inside another array.

   • Let’s say we want to create a salary data structure with multiple employees. We can use either of the following methods:

      

     Method 1 (Using Separate 1D Arrays):

     JavaScript

      

     let arr1 = ["ABC", 24, 18000];
     let arr2 = ["EFG", 30, 30000];
     let arr3 = ["IJK", 28, 41000];
     let arr4 = ["EFG", 31, 28000];
     let arr5 = ["EFG", 29, 35000];
     
     // Combine the individual arrays into a multidimensional array
     let salary = [arr1, arr2, arr3, arr4, arr5];
     

      

     Method 2 (Using Array Literals):

     JavaScript

      

     let salary = [
       ["ABC", 24, 18000],
       ["EFG", 30, 30000],
       ["IJK", 28, 41000],
       ["EFG", 31, 28000]
     ];
     

      

3. Accessing Elements in a Multidimensional Array:

   • To access elements, use index-based notation. For example:
     • salary[0][2] retrieves the salary of the person with the name “ABC” (which is 18000).
     • salary[3][2] retrieves the salary of the person with the name “EFG” (which is 28000).
   • For iterating through the entire array, use nested loops:JavaScript

      

     for (let i = 0; i < salary.length; i++) {
       for (let j = 0; j < salary[i].length; j++) {
         console.log(salary[i][j]);
       }
     }
     

      

4. Adding Elements to a Multidimensional Array:

   • You can add elements to the inner arrays or the outer array.
   • To add an element to the 4th sub-array (e.g., “EFG”), you can use either of the following:JavaScript

      

     // Using square bracket notation
     salary[3][3] = "India"; // Adds "India" at the 4th index of the 4th sub-array
     
     // Using push() method
     salary[3].push("India", "Mumbai"); // Adds "India" and "Mumbai" to the 4th sub-array
     
     

Remember that multidimensional arrays in JavaScript are essentially arrays inside another array, allowing you to organize data in a structured manner.