JS基础教程：2023.3.20第二十二天-JavaScript web APIs-Dom事件基础

前言

记录时间：2023.3.20

坚持的第二十二天

JavaScript从入门到精通

学习javascript时间历程记录打卡

晚上8:30到22：30

JS-Dom事件基础总结

完成代码练习

1.键盘事件类型

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <input type="text">
  <script>
    const input = document.querySelector('input')
    // 1. 键盘事件
    // input.addEventListener('keydown', function () {
    //   console.log('键盘按下了')
    // })
    // input.addEventListener('keyup', function () {
    //   console.log('键盘谈起了')
    // })
    // 2. 用户输入文本事件  input
    input.addEventListener('input', function () {
      console.log(input.value)
    })
  </script>
</body>

</html>

2.focus选择器

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    input {
      width: 200px;
      transition: all .3s;
    }

    /* focus伪类选择器  获得焦点 */
    input:focus {
      width: 300px;
    }
  </style>
</head>

<body>
  <input type="text">
</body>

</html>

3.评论回车发布

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>评论回车发布</title>
  <style>
    .wrapper {
      min-width: 400px;
      max-width: 800px;
      display: flex;
      justify-content: flex-end;
    }

    .avatar {
      width: 48px;
      height: 48px;
      border-radius: 50%;
      overflow: hidden;
      background: url(./images/avatar.jpg) no-repeat center / cover;
      margin-right: 20px;
    }

    .wrapper textarea {
      outline: none;
      border-color: transparent;
      resize: none;
      background: #f5f5f5;
      border-radius: 4px;
      flex: 1;
      padding: 10px;
      transition: all 0.5s;
      height: 30px;
    }

    .wrapper textarea:focus {
      border-color: #e4e4e4;
      background: #fff;
      height: 50px;
    }

    .wrapper button {
      background: #00aeec;
      color: #fff;
      border: none;
      border-radius: 4px;
      margin-left: 10px;
      width: 70px;
      cursor: pointer;
    }

    .wrapper .total {
      margin-right: 80px;
      color: #999;
      margin-top: 5px;
      opacity: 0;
      transition: all 0.5s;
    }

    .list {
      min-width: 400px;
      max-width: 800px;
      display: flex;
    }

    .list .item {
      width: 100%;
      display: flex;
    }

    .list .item .info {
      flex: 1;
      border-bottom: 1px dashed #e4e4e4;
      padding-bottom: 10px;
    }

    .list .item p {
      margin: 0;
    }

    .list .item .name {
      color: #FB7299;
      font-size: 14px;
      font-weight: bold;
    }

    .list .item .text {
      color: #333;
      padding: 10px 0;
    }

    .list .item .time {
      color: #999;
      font-size: 12px;
    }
  </style>
</head>

<body>
  <div class="wrapper">
    <i class="avatar"></i>
    <textarea id="tx" placeholder="发一条友善的评论" rows="2" maxlength="200"></textarea>
    <button>发布</button>
  </div>
  <div class="wrapper">
    <span class="total">0/200字</span>
  </div>
  <div class="list">
    <div class="item" style="display: none;">
      <i class="avatar"></i>
      <div class="info">
        <p class="name">清风徐来</p>
        <p class="text">大家都辛苦啦，感谢各位大大的努力，能圆满完成真是太好了[笑哭][支持]</p>
        <p class="time">2022-10-10 20:29:21</p>
      </div>
    </div>
  </div>
  <script>
    const tx = document.querySelector('#tx')
    const total = document.querySelector('.total')
    // 1. 当我们文本域获得了焦点，就让 total 显示出来
    tx.addEventListener('focus', function () {
      total.style.opacity = 1
    })
    // 2. 当我们文本域失去了焦点，就让 total 隐藏出来
    tx.addEventListener('blur', function () {
      total.style.opacity = 0
    })
    // 3. 检测用户输入
    tx.addEventListener('input', function () {
      // console.log(tx.value.length)  得到输入的长度
      total.innerHTML = `${tx.value.length}/200字`
    })

    // const str = 'andy'
    // console.log(str.length)
  </script>
</body>

</html>

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THE END