如何让 javascript 显示随机名称而不重复？

Question

我需要能够单击一个按钮，然后以随机顺序出现几个不同的名称，而不会重复任何名称。显示随机名称很简单，但我无法避免重复。这就是我所拥有的，但我不明白为什么它不起作用。

<script>

var players = []
players[0] = "Billy";
players[1] = "Alex";
players[2] = "Kevin";
players[3] = "Fred";

function tournament(amount) {
    var a = 0, i = 0, place = 1;
    randomlyselect:
    while (a<amount) {
        var randomplayer = Math.floor(Math.random()*(players.length));
        if (players[randomplayer] === document.getElementById('player1').innerHTML || document.getElementById('player2').innerHTML || document.getElementById('player3').innerHTML) {
            continue randomlyselect;
            } 
        else {
            document.getElementById('player'+place).innerHTML = players[randomplayer];
            place++;
            a++;
        }
    }

}

</script>

<button onClick="tournament(4)">Tournament Results</button>

<p id="player1"></p>
<p id="player2"></p>
<p id="player3"></p>
<p id="player4"></p>

我知道问题在于 if 语句，但我不知道如何检查名称是否已显示。如果您知道我检查某些东西是否已经被挑选的方法有什么问题，或者是避免重复的更好方法，请告诉我。

Answer 1

这是一个通用函数方法，用于创建一个新数组，其中原始数组的值以随机顺序而不重复：

function randomizeArrayValues(arr) {
    return String(Array(arr.length))
           .split(',')
           .map(
              function () {
                return this
                       .splice(Math.floor((Math.random()*this.length)), 1)
                       .pop();
              }, 
              arr.slice()
    );
}

// example
// -------
var players = ["Billy", "Alex", "Kevin", "Fred", "Mary", "Beth"];
var trial = 10;

while (trial--) {
 document.querySelector('#result').textContent += 
      randomizeArrayValues(players).join(', ') + '\n';
}

<pre id="result"></pre>

Answer 2

您可以克隆原始数组，然后将其中的项目一一拼接。这样，您将保证每次都能获得独特的结果。

var players = ["Billy", "Alex", "Kevin", "Fred"];

function tournament(amount) {
  
    var clone = players.slice(), i, player;

    for (var i = 0; i < amount; i++) {
        player = clone.splice(Math.floor(Math.random() * clone.length), 1);
        document.getElementById('player' + (i + 1)).innerHTML = player;
    }
}

<button onClick="tournament(4)">Tournament Results</button>

<p id="player1"></p>
<p id="player2"></p>
<p id="player3"></p>
<p id="player4"></p>

但请注意，由于它会创建数组的副本，因此这种方法在玩家数组非常大的情况下可能并不理想。

Answer 3

我会从数组中切出每个选择，这样就无法再次选择它，然后将其写入循环中。

var randomplayer = Math.floor(Math.random()*(players.length));
players = players.slice(randomplayer, 1);

编辑：让我编写整个函数以防万一出现混乱。

function tournament(){
    var place = 1;
    while(players.length > 0){
        var randomplayer = Math.floor(Math.random()*(players.length));
        document.getElementById('player'+place).innerHTML = players[randomplayer];
        players = players.slice(randomplayer, 1);
        place++;
    }
}

Answer 4

var players = []
players[0] = "Billy";
players[1] = "Alex";
players[2] = "Kevin";
players[3] = "Fred";


function tournament(amount) {
  var randomOrder = shuffle(players)
  var count = Math.min(amount, randomOrder.length)
  for (var i = 0; i < count; ++i) {
    document.getElementById("player" + (i + 1)).textContent = randomOrder[i]
  }
}

// http://stackoverflow.com/a/2450976/4339170
function shuffle(array) {
  var currentIndex = array.length,
    temporaryValue, randomIndex;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;
  }

  return array;
}

<button onClick="tournament(4)">Tournament Results</button>

<p id="player1"></p>
<p id="player2"></p>
<p id="player3"></p>
<p id="player4"></p>