按下回车发布评论案例

  1. 当我们文本域获得了焦点,就让total显示出来
  2. 当我们文本域失去了焦点,就让total隐藏出来
  3. 检测用户输入
  4. 按下回车发布评论
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 20:29:21p>
      div>
    div>
  div>

  <script>
    const tx=document.querySelector('#tx')
    const total=document.querySelector('.total')
    const item=document.querySelector('.item')
    const text=document.querySelector('.text')
    // 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(){
      total.innerHTML=`${tx.value.length}/200字`
    })
    // 4.按下回车发布评论
    tx.addEventListener('keyup',function(e){
        // 只有按下的是回车键,才会触发
        if(e.key ==='Enter'){
            if(tx.value.trim()!==''){       //trim()方法去除字符串左右的空格
                item.style.display='block'
                text.innerHTML=tx.value
            }
            // 等我们按下回车,结束,清空文本域
            tx.value=''
            // 按下回车之后,就要把字符串统计复原
            total.innerHTML='0/200字'
        }
    })
    // 5.
  script>
body>

html>

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