JavaScript 2D Array

1. Array Constructor to Create 2D Array in JavaScript
2. Array Literal Notion to Create 2D Array in JavaScript
3. the Array.from() Method to Create 2D Array in JavaScript
4. the Array.prototype.map() Method to Create 2D Array in JavaScript

This tutorial introduces how to declare a two-dimensional array in JavaScript. In two dimensional array, the items are organized as a matrix in the form of rows and columns. It is like an array whose elements are one-dimensional arrays.

Array Constructor to Create 2D Array in JavaScript

We use the array constructor to create an empty array of the given length. We can then use a for loop to create an array for each element.

const m = 4;
const n = 5;

let arr = new Array(m);

for (var i = 0; i < m; i++) {
  arr[i] = new Array(n);
}

console.log(arr);

Output:

Array [ [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ] ]

Array Literal Notion to Create 2D Array in JavaScript

We can use the literal notation method to create 2D arrays in JavaScript.

const m = 4;
const n = 5;
let arr = [];

for (var i = 0; i < m; i++) {
  arr[i] = [];
}

console.log(arr);

Output:

Array [ [], [], [], [] ]

the Array.from() Method to Create 2D Array in JavaScript

The Array.from() method returns an array object from any JavaScript object.

const m = 4;
const n = 5;

let arr = Array.from(Array(m), () => new Array(n));

console.log(arr);

Output:

Array [ [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ] ]

the Array.prototype.map() Method to Create 2D Array in JavaScript

The Array.map() method also helps create a 2D array by mapping array elements to an empty array.

const m = 4;
const n = 5;
let arr = Array(m).fill().map(() => Array(n));
console.log(arr);

Output:

Array [ [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ], [ null, null, null, null, null ] ]