array_shuffle.js

Array.prototype.shuffle = function () {
  let c = [];
  const MAX = this.length;

  function testAndShuffle(item) {
    let index = Math.floor(Math.random() * MAX);

    if (typeof c[index] === "undefined") {
      c[index] = item;
    } else {
      testAndShuffle(item);
    }
  }
  this.forEach((item) => testAndShuffle(item));

  return c;
};

console.log([1, 2, 3, 4, 5, 6].shuffle());
console.log([1, 2, 3, 4, 5, 6].shuffle());
console.log([1, 2, 3, 4, 5, 6].shuffle());