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基于JavaScript实现猜数字游戏代码实例

2020年07月30日 作者：波尔原文

环境

  • vscode 1.46
  • Microsoft Edge 83

示例

以下内容为了解和熟悉 JavaScript，不需要理解，能够复制粘贴并正确运行即可。

新建网页模板

在 vscode 中新建一个 index.html 文件，然后输入以下内容。

<!DOCTYPE html>
<html>
 <head>
  <meta charset="utf-8">

  <title>猜数字游戏</title>

  <style>
   html {
    font-family: sans-serif;
   }

   body {
    width: 50%;
    max-width: 800px;
    min-width: 480px;
    margin: 0 auto;
   }

   .lastResult {
    color: white;
    padding: 3px;
   }
  </style>
 </head>

 <body>
  <h1>猜数字游戏</h1>

  <p>我刚才随机选定了一个100以内的自然数。看你能否在 10 次以内猜中它。每次我都会告诉你所猜的结果是高了还是低了。</p>

  <div class="form">
   <label for="guessField">请猜数: </label>
   <input type="text" id="guessField" class="guessField">
   <input type="submit" value="确定" class="guessSubmit">
  </div>

  <div class="resultParas">
   <p class="guesses"></p>
   <p class="lastResult"></p>
   <p class="lowOrHi"></p>
  </div>

  <script>

   // 开始编写 JavaScript 代码

  </script>
 </body>
</html>

定义变量

首先将需要使用的变量都定义出来。

let randomNumber = Math.floor(Math.random() * 100) + 1;

const guesses = document.querySelector('.guesses');
const lastResult = document.querySelector('.lastResult');
const lowOrHi = document.querySelector('.lowOrHi');

const guessSubmit = document.querySelector('.guessSubmit');
const guessField = document.querySelector('.guessField');

let guessCount = 1;
let resetButton;

定义猜数字主逻辑

function checkGuess() {
 let userGuess = Number(guessField.value);
 if (guessCount === 1) {
  guesses.textContent = '上次猜的数：';
 }
 guesses.textContent += userGuess + ' ';
 
 if (userGuess === randomNumber) {
  lastResult.textContent = '恭喜你！猜对了';
  lastResult.style.backgroundColor = 'green';
  lowOrHi.textContent = '';
  setGameOver();
 } else if (guessCount === 10) {
  lastResult.textContent = '!!!GAME OVER!!!';
  setGameOver();
 } else {
  lastResult.textContent = '你猜错了！';
  lastResult.style.backgroundColor = 'red';
  if(userGuess < randomNumber) {
   lowOrHi.textContent = '你猜低了！';
  } else if(userGuess > randomNumber) {
   lowOrHi.textContent = '你猜高了';
  }
 }
 
 guessCount++;
 guessField.value = '';
 guessField.focus();
}

结束游戏

function setGameOver() {
 guessField.disabled = true;
 guessSubmit.disabled = true;
 resetButton = document.createElement('button');
 resetButton.textContent = '开始新游戏';
 document.body.appendChild(resetButton);
 resetButton.addEventListener('click', resetGame);
}

重置游戏

function resetGame() {
 guessCount = 1;

 const resetParas = document.querySelectorAll('.resultParas p');
 for (let i = 0 ; i < resetParas.length; i++) {
  resetParas[i].textContent = '';
 }

 resetButton.parentNode.removeChild(resetButton);

 guessField.disabled = false;
 guessSubmit.disabled = false;
 guessField.value = '';
 guessField.focus();

 lastResult.style.backgroundColor = 'white';

 randomNumber = Math.floor(Math.random() * 100) + 1;
}

浏览器打开

用浏览器打开刚刚编写的程序，试试游戏是否能够正常运行。

附录

源码

<!DOCTYPE html>
<html>

<head>
 <meta charset="utf-8">
 <title>猜数字游戏</title>
 <style>
  html {
   font-family: sans-serif;
  }

  body {
   width: 50%;
   max-width: 800px;
   min-width: 480px;
   margin: 0 auto;
  }

  .lastResult {
   color: white;
   padding: 3px;
  }
 </style>
</head>

<body>
 <h1>猜数字游戏</h1>

 <p>我刚才随机选定了一个100以内的自然数。看你能否在 10 次以内猜中它。每次我都会告诉你所猜的结果是高了还是低了。</p>

 <div class="form">
  <label for="guessField">请猜数: </label>
  <input type="text" id="guessField" class="guessField">
  <input type="submit" value="确定" class="guessSubmit">
 </div>

 <div class="resultParas">
  <p class="guesses"></p>
  <p class="lastResult"></p>
  <p class="lowOrHi"></p>
 </div>

 <script>

  let randomNumber = Math.floor(Math.random() * 100) + 1;

  const guesses = document.querySelector('.guesses');
  const lastResult = document.querySelector('.lastResult');
  const lowOrHi = document.querySelector('.lowOrHi');

  const guessSubmit = document.querySelector('.guessSubmit');
  const guessField = document.querySelector('.guessField');

  let guessCount = 1;
  let resetButton;

  function checkGuess() {
   let userGuess = Number(guessField.value);
   if (guessCount === 1) {
    guesses.textContent = '上次猜的数：';
   }
   guesses.textContent += userGuess + ' ';

   if (userGuess === randomNumber) {
    lastResult.textContent = '恭喜你！猜对了';
    lastResult.style.backgroundColor = 'green';
    lowOrHi.textContent = '';
    setGameOver();
   } else if (guessCount === 10) {
    lastResult.textContent = '!!!GAME OVER!!!';
    setGameOver();
   } else {
    lastResult.textContent = '你猜错了！';
    lastResult.style.backgroundColor = 'red';
    if (userGuess < randomNumber) {
     lowOrHi.textContent = '你猜低了！';
    } else if (userGuess > randomNumber) {
     lowOrHi.textContent = '你猜高了';
    }
   }

   guessCount++;
   guessField.value = '';
   guessField.focus();
  }

  guessSubmit.addEventListener('click', checkGuess);

  function setGameOver() {
   guessField.disabled = true;
   guessSubmit.disabled = true;
   resetButton = document.createElement('button');
   resetButton.textContent = '开始新游戏';
   document.body.appendChild(resetButton);
   resetButton.addEventListener('click', resetGame);
  }

  function resetGame() {
   guessCount = 1;

   const resetParas = document.querySelectorAll('.resultParas p');
   for (let i = 0; i < resetParas.length; i++) {
    resetParas[i].textContent = '';
   }

   resetButton.parentNode.removeChild(resetButton);

   guessField.disabled = false;
   guessSubmit.disabled = false;
   guessField.value = '';
   guessField.focus();

   lastResult.style.backgroundColor = 'white';

   randomNumber = Math.floor(Math.random() * 100) + 1;
  }

 </script>
</body>
</html>

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