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.
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.
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)
}
}
}
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));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);
a[0][0]will have an array, buta[0][1]will beundefined. If you try to explain what you are trying to achieve, we could recommend something