Function to shuffle the values of an array (Use case: simulating dice rolls for games without an RNG)

array-shuffle.js

/**
 * Shuffles an array and optionally returns a specified number of elements from the shuffled array.
 *
 * @param {Array} arr - The array to be shuffled.
 * @param {number} [size=0] - The number of elements to return from the shuffled array. 
 *                            If 0, the entire shuffled array is returned. Defaults to 0.
 * @returns {Array} A new array containing the shuffled elements. If `size` is specified, 
 *                  the array will contain only the first `size` elements of the shuffled array.
 *
 * @example
 * // Shuffles the array and returns all elements in random order
 * let shuffledArray = shuffle([1, 2, 3, 4, 5]);
 * console.log(shuffledArray); // e.g., [3, 1, 4, 5, 2]
 *
 * @example
 * // Shuffles the array and returns only 3 elements from the shuffled array
 * let partialShuffledArray = shuffle([1, 2, 3, 4, 5], 3);
 * console.log(partialShuffledArray); // e.g., [4, 2, 5]
 */
function shuffle(arr, size = 0) {
    let newArray = [];

    do {
        // get a random position of the arr
        let random = Math.floor(Math.random() * arr.length);

        //add the value of that position to the new array
        newArray.push(arr[random]);

        // remove the position of the arr
        arr = arr.filter((v, k) => k !== random);
    } while (arr.length > 0);

    if (size > 0) {
      newArray = newArray.slice(0, size);
    }

    return newArray;
}

// Example of random order of a D6
let d6Array = Array.from({ length: 6 }, (value, index) => index + 1);
console.log(shuffle(d6Array)); 

// Example of a D20 roll
let d20Array = Array.from({ length: 20 }, (value, index) => index + 1);
console.log(shuffle(d20Array, 1));