How to create multiple arrays of random numbers in js?

Question

I am attempting to create a matrix of 3 arrays with 10 elements in each array. Each element should be a random number between 1 and 10. I wanted to use a single function to generate each of the arrays, and used this:

var array1 = [];
var array2 = [];
var array3 = [];

var tempName;

function fcnArrayGenerate(){
    let i = 1;
    while (i < 4){
        tempName = "array" + i;
        let j = 0;
        while (j < 10){
            tempName.push((Math.floor(Math.random() * 10) + 1));
            j++;
        }
        i++;
    }
    console.log(array1);
    console.log(array2);
    console.log(array3);
}

However, when I run the function, I receive an error stating that "tempName.push is not a function." Any assistance on how to correct this would be appreciated. Thank you.

"array" + i will not reference the array1 variable, but it will be a string "array1". tempName will be a string and string does not have push method, hence the error. You can create a multidimensional array in javascript. var array = [[1,8], [2,9], [3,5]]. Try that. — Jashwant
– Jashwant, Commented Apr 17, 2022 at 5:41

Amit · Accepted Answer · 2022-04-17 05:57:43Z

2

Instead of using three variables for three different arrays, you can use a single multidimensional array to store those three arrays.

let array = [[], [], []];

function fcnArrayGenerate() {
  let i = 0;
  while (i <= 2) {
    let j = 0;
    while (j < 10) {
      array[i].push(Math.floor(Math.random() * 10) + 1);
      j++;
    }
    i++;
  }
}
// call the function
fcnArrayGenerate();
// now print the arrays as tables
console.table(array);
console.table(array[0]);
console.table(array[1]);
console.table(array[2]);

Note: console.table() allows you to print out arrays and objects to the console in tabular form.

answered Apr 17, 2022 at 5:57

Amit

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1 Comment

Michael Over a year ago

This was an elegant solution and exactly what I was looking for. The initial array declaration will be a bit tedious in that my full scale run will require a matrix of 68x38, but at least I was able to scale it down from 170x95. Thank you for your help.

ABGR · Accepted Answer · 2022-04-17 05:55:21Z

1

If you want to push into tempName you have to initialise it with an empty array first. Right now it’s undefined. Hence you’re seeing the error as you can’t push something to undefined

Do this: var tempName = []

answered Apr 17, 2022 at 5:55

ABGR

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Comments

s.kuznetsov · Accepted Answer · 2022-04-17 06:15:28Z

0

To make variable names incremental, you can pass them as objects.

var data = {
  array1: [],
  array2: [],
  array3: []
}

function fcnArrayGenerate(){
    let i = 1;
    while (i < 4){
        let j = 0;
        while (j < 10){
            data['array' + i].push((Math.floor(Math.random() * 10) + 1));
            j++;
        }
        i++;
    }
    console.log(data.array1);
    console.log(data.array2);
    console.log(data.array3);
}

fcnArrayGenerate();

answered Apr 17, 2022 at 6:15

s.kuznetsov

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