Trying to create a matrix with random numbers in JavaScript produces a matrix where all the rows are the same

Question

When I try to create a matrix with random numbers, the matrix rows all appear the same. How do I fix this? The code for the problem is:

var sudokuRowMatrix = [];
var numbers = [];
var randomizedArray = [];
var sudokuColumnArray = [];
for(i=0;i<=8;i++){
    numbers[i]=i+1;
    sudokuRowMatrix[i] = [];
    sudokuColumnArray[i] = [];
}

function RandomizeArray(array){
    for(arrayIndex=0;arrayIndex<=8;arrayIndex++){
        randomArrayIndex = Math.floor(Math.random()*9);
        randomArrayIndex2 = Math.floor(Math.random()*9);
        placeHolder = array[randomArrayIndex];
        array[randomArrayIndex]=array[randomArrayIndex2];
        array[randomArrayIndex2] = placeHolder;
    }
    return array;
}

for(rowNumber=0;rowNumber<=8;rowNumber++){
    sudokuRowMatrix[rowNumber] = RandomizeArray(numbers);
}

score 2 · Accepted Answer · answered Aug 17 '21 at 13:31

2

When you call RandomizeArray(numbers) you pass the numbers array as a reference. This means, that you always shuffle the same array and set it as a row in your Sudoku matrix and therefore shuffle all of your rows since they all hold the same reference.

An easy way to fix this, is to destructure your array before passing it to your method: sudokuRowMatrix[rowNumber] = RandomzieArray([...numbers]);

You can find my source here.

answered Aug 17 '21 at 13:31

Marco Wagner

457
4
17

Is there a way to pass the numbers array by value? – WaterL00 Aug 17 '21 at 13:53
1

@WaterL00 No, but there are workarounds: https://stackoverflow.com/questions/7574054/javascript-how-to-pass-object-by-value – Marco Wagner Aug 18 '21 at 08:53

Trying to create a matrix with random numbers in JavaScript produces a matrix where all the rows are the same

1 Answers1