先看效果如下
jokes-LMLPHP
目录如下

//index.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
  <meta name="viewport" content="width=device-width">
  <title>笑话生成器</title>
  <link rel="stylesheet" href="style.css">
  <script src="ui.js" defer></script>
  <script src="main.js" defer></script>
</head>

<body>
  <div>
    <label for="customname" id="lbl-customname">请输入自定义的名字:</label>
    <input id="customname" type="text" placeholder="李雷">
  </div>
  <div>
    <label for="cn" id="lbl-cn">中国</label>
    <input id="cn" type="radio" name="country" value="cn" checked>
    <label for="us" id="lbl-us">美国</label>
    <input id="us" type="radio" name="country" value="us">
    <label for="uk" id="lbl-uk">英国</label>
    <input id="uk" type="radio" name="country" value="uk">
  </div>
  <div>
    <button class="randomize">随机生成笑话</button>
  </div>
  <p class="story"></p>
</body>
</html>
//main.js
const customName = document.getElementById('customname');
const randomize = document.querySelector('.randomize');
const story = document.querySelector('.story');

function randomValueFromArray(array){
  const random = Math.floor(Math.random()*array.length);
  return array[random];
}

const storyText = 'It was 94 fahrenheit outside, so :insertx: went for a walk. When they got to :inserty:, they stared in horror for a few moments, then :insertz:. Bob saw the whole thing, but was not surprised — :insertx: weighs 300 pounds, and it was a hot day.';
const insertX = ['Willy the Goblin','Big Daddy','Father Christmas'];
const insertY = ['the soup kitchen','Disneyland','the White House'];
const insertZ = ['spontaneously combusted','melted into a puddle on the sidewalk','turned into a slug and crawled away'];

const storyTextZh = '外边有34度,于是:inserta:出去遛弯。当走到:insertb:时他们被眼前的景象惊呆了,然后就:insertc:。李雷全程目睹但他并没有慌,因为:inserta:是一个270斤的胖子,天气又辣么热。';
const insertA = ['怪兽威利', '大老爹', '圣诞老人'];
const insertB = ['救助站', '迪士尼乐园', '白宫'];
const insertC = ['自燃了', '在人行道化成了一坨泥', '变成一条鼻涕虫爬走了'];

randomize.addEventListener('click', result);

function result() {
  let newStory, xItem, yItem, zItem, name;
  if (document.getElementById('cn').checked) {
    newStory = storyTextZh;

    xItem = randomValueFromArray(insertA);
    yItem = randomValueFromArray(insertB);
    zItem = randomValueFromArray(insertC);

    newStory = newStory.replace(':inserta:', xItem);
    newStory = newStory.replace(':inserta:', xItem);
    newStory = newStory.replace(':insertb:', yItem);
    newStory = newStory.replace(':insertc:', zItem);

    if (customName.value !== '') {
      name = customName.value;
      newStory = newStory.replace('李雷', name);
    }
  } else {
    newStory = storyText;

    xItem = randomValueFromArray(insertX);
    yItem = randomValueFromArray(insertY);
    zItem = randomValueFromArray(insertZ);

    newStory = newStory.replace(':insertx:', xItem);
    newStory = newStory.replace(':insertx:', xItem);
    newStory = newStory.replace(':inserty:', yItem);
    newStory = newStory.replace(':insertz:', zItem);

    if (customName.value !== '') {
      name = customName.value;
      newStory = newStory.replace('Bob', name);
    }

    if (document.getElementById("uk").checked) {
      const weight = Math.round(300 * 0.0714286) + ' stone';
      const temperature = Math.round((94 - 32) * 5 / 9) + ' centigrade';
      newStory = newStory.replace('94 fahrenheit', temperature);
      newStory = newStory.replace('300 pounds', weight);
    }
  }

  story.textContent = newStory;
  story.style.visibility = 'visible';
}

//style.css
body {
    font-family: helvetica, sans-serif;
    width: 350px;
    border: 1px solid;
    padding: 1em;
}

label {
  font-weight: bold;
}

div {
  padding-bottom: 20px;
}

input[type="text"] {
  padding: 5px;
  width: 150px;
}

p {
  background: #FFC125;
  color: #5E2612;
  padding: 10px;
  visibility: hidden;
}
//ui.js
document.getElementById('cn').onclick = () => {
    document.title = '笑话生成器';
    document.getElementById('lbl-customname').textContent = '请输入自定义的名字:';
    document.getElementById('lbl-cn').textContent = '中国';
    document.getElementById('lbl-us').textContent = '美国';
    document.getElementById('lbl-uk').textContent = '英国';
    document.getElementById('customname').placeholder = '李雷';
    document.querySelector('.randomize').textContent = '随机生成笑话';
  };

  document.getElementById('us').onclick =
  document.getElementById('uk').onclick = () => {
    document.title = 'Silly story generator';
    document.getElementById('lbl-customname').textContent = 'Enter custom name:';
    document.getElementById('lbl-cn').textContent = 'CN';
    document.getElementById('lbl-us').textContent = 'US';
    document.getElementById('lbl-uk').textContent = 'UK';
    document.getElementById('customname').placeholder = 'Bob';
    document.querySelector('.randomize').textContent = 'Generate random story';
  };
05-01 05:20