three-dimensional array in javascript

Question

var a = new Array();
var b  = [1,2,3,4,5,6,7];
for(i in b){a[i] = new Array(new Array());}
a[0][1][2] = Math.random();// error:VM205:1 Uncaught TypeError: Cannot set property '2' of undefined(…)

How to use three-dimensional array in javascript?

i mean how to use it like java.
eg: double a = new double[length][length][length];

how to memorize memory in advance.

You need to initialize each array with the values you want. There's no true multi-dimensional array that will be fully allocated with merely a declaration. — , Nov 01 '16 at 12:03
Its because, new Array will set an array of length 0. So `a[0][0]` will have an array, but `a[0][1]` will be `undefined`. If you try to explain what you are trying to achieve, we could recommend something — Rajesh, Nov 01 '16 at 12:04
Possible duplicate: http://stackoverflow.com/questions/7545641/javascript-multidimensional-array — teroi, Nov 01 '16 at 12:05

rishat · Accepted Answer · 2016-11-02T02:32:34.077

In Javascript, there's no use in instantiating variables in advance, and there is no such thing as compile-time memory allocation because, hey, there's no compile time! But if you really want to do it, it's not as trivial as in Java:

const length = 7;
const range = new Array(length).fill();
const array = range.map(e => range.map(e => range.map(e => e)));

console.log(JSON.stringify(array)); // -> "[[[null,null,null],[null,null,null],[null,null,null]],[[null,null,null],[null,null,null],[null,null,null]],[[null,null,null],[null,null,null],[null,null,null]]]"

The only point in it is that you can be always sure that, as long as you stay in [0, length) boundaries, array[x][y][z] for any x, y and z will not throw a TypeError.

score 1 · Answer 2 · answered Nov 01 '16 at 12:37

1

you can do like this

const items = [[[]]] // init 3d array

// assign values
items[0][0][0] = 0
items[0][0][1] = 1
items[0][0][2] = 2

// display
for (const i of items) {
  for (const j of i) {
    for (const k of j) {
      console.log('k = ', k)
    }
  }
}

answered Nov 01 '16 at 12:37

Alongkorn

3,968
1
24
41

i mean how to use it like java. eg: double a = new double[length][length][length]; – Cery Nov 02 '16 at 01:15

score 1 · Answer 3 · answered Nov 17 '19 at 12:53

1

Similar to rishat's answer, but has different length.

const array1 = Array(2).fill().map(e => Array(4).fill().map(e => Array(3).fill("3").map(e => e)));
console.log(JSON.stringify(array1));

answered Nov 17 '19 at 12:53

Kelen Nihomori

13
3

Michael Twohey · Answer 4 · 2023-05-25T00:13:32.327

I took this approach in my current project:

    const sourceImage = [1,2,3,255,4,5,6,255,7,8,9,255,10,11,12,255 ]; // RGBA - 16
    
    let noAlphaImage = [];
    
    for (var i = 0; i < sourceImage.length; i++)
    {       
        if (i % 4 !== 3)
        {
            noAlphaImage.push(sourceImage[i]); 
        }
    }
    
    console.log(noAlphaImage);
    
    const WIDTH = 2, HEIGHT = 2, PIXEL = 3;
    var destImage = [];
    
    for (var w = 0; w < WIDTH; w++)
    {
        destImage[w] = [];
        for (var h = 0; h < HEIGHT; h++)
        {
            destImage[w][h] = [];
            for (var p = 0; p < PIXEL; p++)
            {
                const destIndex = (w * HEIGHT * PIXEL) + (h * PIXEL) + (p);
                destImage[w][h][p] = noAlphaImage[destIndex];      
            }
        }
    }
    
    console.log(destImage);

three-dimensional array in javascript

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