Example: Shuffle Deck of Cards

// program to shuffle the deck of cards

// declare card elements
const suits = ["Spades", "Diamonds", "Club", "Heart"];
const values = [
  "Ace",
  "2",
  "3",
  "4",
  "5",
  "6",
  "7",
  "8",
  "9",
  "10",
  "Jack",
  "Queen",
  "King",
];

// empty array to contain cards
let deck = [];

// create a deck of cards
for (let i = 0; i < suits.length; i++) {
    for (let x = 0; x < values.length; x++) {
        let card = { Value: values[x], Suit: suits[i] };
        deck.push(card);
    }
}

// shuffle the cards
for (let i = deck.length - 1; i > 0; i--) {
    let j = Math.floor(Math.random() * i);
    let temp = deck[i];
    deck[i] = deck[j];
    deck[j] = temp;
}

console.log('The first five cards are:');

// display 5 results
for (let i = 0; i < 5; i++) {
    console.log(`${deck[i].Value} of ${deck[i].Suit}`)
}

//output
The first five cards are:
4 of Club
5 of Diamonds
Jack of Diamonds
2 of Club
4 of Spades

function shuffle(array) {
  const curIdx = array.length;

  // While there remain elements to shuffle...
  while (0 !== cur_idx) {
    // Pick a remaining element...
    const randIdx = Math.floor(Math.random() * curIdx);
    curIdx -= 1;

    // And swap it with the current element.
    const originalIdx = array[curIdx];
    array[curIdx] = array[randIdx];
    array[randIdx] = originalIdx;
  }
  return array;
}

// Usage of shuffle
const arr = [1, 2, 3, 4, 5, 6];
arr = shuffle(arr);
console.log(arr);

// shorter
function shuffle(array) {
    for (let i = array.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var originalIdx = array[i];
        array[i] = array[j];
        array[j] = originalIdx;
    }
}

//es6
function shuffle_array(array) {
    for (let i = array.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        [array[i], array[j]] = [array[j], array[i]];
    }
}

const shuffleArray = array => {
  for (let i = array.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    const temp = array[i];
    array[i] = array[j];
    array[j] = temp;
  }
}

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const shuffledArray = array.sort((a, b) => 0.5 - Math.random());

// using Array map and Math.random
const shuffledArr = array => array.map(a => ({ sort: Math.random(), value: a })).sort((a, b) => a.sort - b.sort).map(a => a.value);