In this article, we are going to learn about Declare two-dimensional empty array by using JavaScript. A two-dimensional array is also known as a 2D array. It is a data structure in JavaScript that can hold values in rows and columns form. It is an array of arrays. Each element in a 2D array is accessible using two indices, and it is represented as an array[rowIndex][columnIndex].
There are several methods that can be used to add elements to Declare an empty two-dimensional array in JavaScript, which are listed below:
Table of Content
We will explore all the above methods along with their basic implementation with the help of examples.
Approach 1: Using a Loop
In this approach, we are using nested loops to iterate over the rows and columns of the 2D array and initialize each element to a specific value as null or undefined.
Example: In this example, the Empty2DArray function generates a 2D array with the specified number of rows (3) and columns (4) filled with null values. The arr1 is the resulting array.
Javascript
function Empty2DArray(rows, cols) { Â Â Â Â const array = []; Â Â Â Â for (let i = 0; i < rows; i++) { Â Â Â Â Â Â Â Â array[i] = []; Â Â Â Â Â Â Â Â for (let j = 0; j < cols; j++) { Â Â Â Â Â Â Â Â Â Â Â Â array[i][j] = null; Â Â Â Â Â Â Â Â } Â Â Â Â } Â Â Â Â return array; } Â Â const arr1 = Empty2DArray(3, 4); console.log(arr1); |
[ [ null, null, null, null ], [ null, null, null, null ], [ null, null, null, null ] ]
Approach 2: Using the Array() Constructor
JavaScript provides the Array() constructor, which allows us to create an array of a specific length. We can use this constructor to create a 2D array by initializing each element as an empty array.
function createEmpty2DArray(rows, cols) {
return Array.from({ length: rows }, () => Array(cols).fill(null));
};
Example: In this example, the Empty2DArray function uses Array.from() method to create a 2D array with 3 rows and 5 columns, initializing all elements to null. The arr2 holds the result.
Javascript
function Empty2DArray(rows, cols) { Â Â Â Â return Array.from({ length: rows }, Â Â Â Â Â Â Â Â () => Array(cols).fill(null)); } Â Â let arr2 = Empty2DArray(3, 5); console.log(arr2); |
[ [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ] ]
