Generating Non-Repeating Random Numbers in JS

Generating non-repeating random numbers in JS can be achieved using various techniques. Originally, the approach was to check if a newly generated number had already been created by adding it to an array and comparing against it. However, this can lead to a "Maximum call stack size exceeded" error due to excessive recursive calls.

An efficient solution is to generate a randomized list of numbers once and work through it sequentially. This approach eliminates the need for recursive calls and guarantees no repetitions.

Here's an example using a Fisher–Yates Shuffle:

function shuffle(array) {
    var i = array.length,
        j = 0,
        temp;

    while (i--) {
        j = Math.floor(Math.random() * (i 1));
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
    return array;
}

var ranNums = shuffle([1,2,3,4,5,6,7,8,9,10]);

Alternatively, generators can be used for this purpose:

function* shuffle(array) {
    var i = array.length;
    while (i--) {
        yield array.splice(Math.floor(Math.random() * (i 1)), 1)[0];
    }
}

var ranNums = shuffle([1,2,3,4,5,6,7,8,9,10]);

ranNums.next().value; // first random number from array
ranNums.next().value; // second random number from array
...

These techniques provide efficient ways to generate non-repeating random numbers in JavaScript, eliminating issues related to excessive recursive calls.