Javascript - Math.random 函数在 for 循环中调用时返回相同的结果

Question

我有一个 function{computerPlay()} 每次调用它时都会生成一个新的随机数。它从顶部声明的数组中返回一个项目。当我在 console 中测试它时，它按照我希望的方式工作。但是，为了让我的游戏正常运行，我将其置于 for 循环中，并且它会一直返回相同的值，除非我刷新页面。我无法在任何地方找到答案，这是我的第一个问题。我确定代码很草率，所以请忽略它。这是代码。

  let playOptionsArray = ["Rock", "Paper", "Scissors"];
let totalTies = 0;
let playerPoints = 0;
let computerPoints = 0;
let round = 1;

//formats a player's entry so it will match playOptionsArray
  function firstLetterUppercase(string){
    let firstLetter = string.charAt(0);
    let firstLetterCapitalized = firstLetter.toUpperCase();
    let restOfResponse = string.slice(1);
    let formattedResponse = firstLetterCapitalized + restOfResponse;
    return formattedResponse;
  }

//compares player entry to ensure it matches an item on the playOptions array
  function checkPlayerResponse(response){
    if (response === "Rock" || response === "Paper" || response === "Scissors") {
      return response;
    } else {
      return alert("You must choose either 'Rock', 'Paper', or 'Scissor' as your play. Please try again.");
    }
  }

//generates a random option for the computer's play

  function computerPlay() {
    let computerSelection = playOptionsArray[Math.floor(Math.random()*(playOptionsArray.length))];
    return computerSelection;
  }

  let computerSelection = computerPlay();

  function getPlayerSelection() {
    let playerEntry = window.prompt("You are playing the computer in a game of Rock, Paper, Scissors. First player to five points wins. Choose either Rock, Paper, or Scissors as your play", "Rock");
    if (playerEntry != null) {
    let playerEntryLowercase = playerEntry.toLowerCase();
    playerSelection = firstLetterUppercase(playerEntryLowercase);
  } else {
    getPlayerSelection();
  }
    checkPlayerResponse(playerSelection);
    return playerSelection;
  }

  let playerSelection = getPlayerSelection;

//emulates a single round of rock paper scissor
  function singleRound(){
    if (playerSelection === "Rock" && computerSelection === "Scissors"){
      alert('You have won this round. The computer chose ' + computerSelection + '.');
      playerPoints++;
      round++;
    } else if (playerSelection === "Scissors" && computerSelection === "Paper"){
      alert('You have won this round. The computer chose ' + computerSelection + '.');
      playerPoints++;
      round++
    } else if (playerSelection === "Paper" && computerSelection === "Rock"){
      alert('You have won this round. The computer chose ' + computerSelection + '.');
      playerPoints++;
      round++
    } else if (playerSelection === computerSelection){
      alert('You have tied this round. The computer chose ' + computerSelection + '.');
      totalTies++;
    } else {
      alert('Something went wrong. Refresh the page.')
    }
  }

  function updateScore() {
    document.getElementById("player-points").innerHTML = playerPoints;
    document.getElementById("round").innerHTML = round;
    document.getElementById("computer-points").innerHTML = computerPoints;
    document.getElementById("total-ties").innerHTML = totalTies;
  }

//keeps track of player points and ends when a player gets 5 points
 function game() {
    for (round = 0; computerPoints < 5 && playerPoints < 5; round) {
      getPlayerSelection();
      computerPlay();
      singleRound();
      updateScore();
      }
  }

game();

Answer 1

computerPlay 的返回值不会存储在循环中的任何位置。 (应该注意你的 playerSelection 也会发生这种情况)。尝试

for (round = 0; computerPoints < 5 && playerPoints < 5; round) {
  playerSelection = getPlayerSelection();
  computerSelection = computerPlay();
  singleRound();
  updateScore();
}

编辑:@kavakava 的回答提供了一些关于为什么会出现这种情况的见解。