Better Fisher-Yates array shuffle in ES5

better-fisher-yates-shuffle-.js

// 28 March 2020
// Better Fisher-Yates shuffle in ES5
// Supersedes https://gist.github.com/dfkaye/36a4cd28c91d8ee1febb92c1b2b57e04
// Updated 31 March 2020: use Array.from(); fix test sorting; rename at, from, and to variables.

function shuffle(array) {
    var result = Array.from(array);

    /*
     * This version mutates the array being processed.
     * Considered generally unsafe practice, done here
     * for variable lookup speed within the function scope.
     */

    result.forEach(function(v, i, arr, at, from, to) {
        // Create indexes from and to
        at = arr.length - i;
        from = Math.floor(Math.random() * at);
        to = at - 1;
        
        // Swap values from and to
        v = arr[to];
        arr[to] = arr[from];
        arr[from] = v;
    });

    return result;
}

/* Test it out */

var source = Array.from(Array(10)).map((v,i) => i + 1);

Array.from(Array(10))
    .map(() => shuffle(source))
    .sort((a, b) => Number(a.join('')) - Number(b.join('')))
    .forEach(result => console.log(result.join(' ')));
    
/*
    1 2 5 4 10 3 6 7 8 9
    2 1 3 4 9 10 5 6 8 7
    4 10 5 8 1 6 9 3 2 7
    4 10 5 8 9 2 6 1 3 7
    4 5 1 8 3 9 2 10 6 7
    8 2 6 9 7 4 10 5 3 1
    8 7 10 9 1 2 5 6 4 3
    9 3 8 6 5 1 4 7 2 10
    9 4 3 2 5 8 10 6 1 7
    9 8 7 1 4 6 10 5 3 2
*/