Create a 2-dimensional array in JavaScript

This post will discuss how to create a two-dimensional array in JavaScript.

JavaScript offers several ways to create a two-dimensional array of fixed dimensions:

1. Using Array constructor

Using the array constructor and the for-loop, creating a two-dimensional array in JavaScript is as simple as:

const M = 3, N = 4;

var arr = new Array(M); // create an empty array of length `M`

for (var i = 0; i < M; i++) {

arr[i] = new Array(N); // make each element an array

}

console.log(arr);

Output: [ [ <4 empty items> ], [ <4 empty items> ], [ <4 empty items> ] ]

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2. Using array literal notation

2D Arrays can be created using the literal notation, as shown below:

const M = 3, N = 4; // Note 2nd dimension is not relevant here

var arr = [];

for (var i = 0; i < M; i++) {

arr[i] = [];

}

console.log(arr);

Output: [ [], [], [] ]

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3. Using `Array.from()` function

The Array.from() method creates a new Array instance from the specified array and optionally map each array element to a new value. To create a 2D array, the idea is to map each element of the length of M to a new empty array of length N.

const M = 3, N = 4;

var arr = Array.from(Array(M), () => new Array(N));

console.log(arr);

Output: [ [ <4 empty items> ], [ <4 empty items> ], [ <4 empty items> ] ]

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4. Using `Array.prototype.map()` function

Alternatively, you can directly call the map() function on the array, as shown below:

const M = 3, N = 4;

var arr = Array(M).fill().map(() => Array(N));

console.log(arr);

Output: [ [ <4 empty items> ], [ <4 empty items> ], [ <4 empty items> ] ]

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That’s all about creating a two-dimensional array in JavaScript.

Create a 2-dimensional array in JavaScript

1. Using Array constructor

2. Using array literal notation

3. Using Array.from() function

4. Using Array.prototype.map() function

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3. Using `Array.from()` function

4. Using `Array.prototype.map()` function