how to create nxn matrix/array in javascript?

Question

I want to create an array or matrix with non-fixed number of rows like

var matrix=[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]

how can i do that?

• str: Possible duplicate of Matrix of numbers javascript
• Steffen Harbich: What is stopping you from just doing it as you already wrote it? See here for multi dimensional array access.

Answer 1

An ES6 solution using Array.from and Array#fill methods.

function matrix(m, n) {
 return Array.from({
 // generate array of length m
 length: m
 // inside map function generate array of size n
 // and fill it with `0`
 }, () => new Array(n).fill(0));
};
console.log(matrix(3,2));

Answer 2

For enhanced readability

const create = (amount) => new Array(amount).fill(0);
const matrix = (rows, cols) => create(cols).map((o, i) => create(rows))
console.log(matrix(2,5))

For less code

const matrix = (rows, cols) => new Array(cols).fill(0).map((o, i) => new Array(rows).fill(0))
console.log(matrix(2,5))

Answer 3

you can alse use the code like:

function matrix(m, n) {
 var result = []
 for(var i = 0; i < n; i++) {
 result.push(new Array(m).fill(0))
 }
 return result
}
console.log(matrix(2,5))

• Madhav: is it possible to get same result without using .fill() ?

Answer 4

I use the following ES5 code:

var a = "123456".split("");
var b = "abcd".split("");
var A = a.length;
var B = b.length;
var t= new Array(A*B);
for (i=0;i<t.length;i++) {t[i]=[[],[]];} 
t.map(function(x,y) {
 x[0] = a[parseInt(y/B)];
 x[1] = b[parseInt(y%B)];
 }); 
t;

It returns a 2d array and obviously your input doesn't have to be strings.

For some amazing answers in ES6 and other languages check out my question in stack exchange, ppcg.

Answer 5

function createArray(row, col) {
 let matrix = [];
 for (let i = 0; i < row; i++) {
 matrix.push([]);
 for (let j = 0; j < col; j++) {
 matrix[i].push([]);
 }
 }
 console.log(matrix);
}
createArray(2, 3);

OUTPUT:- [ [ [], [], [] ], [ [], [], [] ] ]

note: if you want to get array with values, like [ [ [1], [1], [1] ], [ [1], [1], [1] ] ] then replace 6th line of code with matrix[i].push([1]);

Answer 6

Can be done like this:

Array(n).fill(Array(m).fill(0))

where

n - number of rows
m - number of columns

• askhat: Each row will reference the same object! That's probably isn't desired
• pobu: right, see what happens if you declare e.g. 5x5 matrix this way and then set a[2][3] = 1