Basically, multi-dimension arrays are used if you want to put arrays inside an array. Let's take an example. Say you wanted to store every 6 hour's temperature for every weekday. You could do something like:
let monday = [35, 28, 29, 31]; let tuesday = [33, 24, 25, 29]; //...
This is a good place to use a multidimensional array instead. A multidimensional array is nothing but an array of arrays. If we take forward our example, each row will represent a day while each entry in the row will represent a temp entry. For example,
let temps = [ [35, 28, 29, 31], [33, 24, 25, 29] ];
You can chain array access. For example, if you want the 3rd element in the second row, you could just query for temps[1][2]. Note that the order is rows than columns. You can iterate these arrays using multiple for loops. For example,
let temps = [
[35, 28, 29, 31],
[33, 24, 25, 29]
];
for (let i = 0; i < 2; i++) {
console.log("Row #" + i) for (let j = 0; j < 4; j++) {
console.log(i, j, temps[i][j])
}
}This will give the output −
Row #0 0 0 35 0 1 28 0 2 29 0 3 31 Row #1 1 0 33 1 1 24 1 2 25 1 3 29
Multidimensional arrays can have more than 2 dimensions as well. Mostly 2 dimensions will suffice, though some places where you can use 3 dimensions are during 3D operations, physics calculations, etc.