留言版案例（js dom操作）用dom实现留言板操作（发布评论）一个非常简单的留言板案例，实现了增删改留言的功能 ht

html操作

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

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./index.css">
</head>

<body>
  <div class="msg">
    <input class="msg_txt" placeholder="请输入文本">
    </input>
    <button class="btn">发布留言</button>
   
  </div>

  <div class="comment">
    <ul></ul>
  </div>
  <script src="./index.js"></script>
</body>

</html>

css操作

* {
  margin: 0;
  padding: 0;
  color: #4e4d4d;
  font-family: '宋体';
  box-sizing: border-box;
}

.msg {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  position: relative;
  width: 100vw;
  height: 20vh;
  background-color: seashell;
}

.msg_txt {
  font-size: 28px;
  padding: 50px;
  width: 100%;
  height: 100%;
}

.btn {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 15vw;
  height: 8vh;
  background-color: #fff;
  font-size: 24px;
}

.comment {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 80vh;
  background-color: #eee;
}

ul {
  width: 80%;
  height: 100%;
}

li {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  width: 100%;
  height: 10%;
  background-color: rgb(238, 245, 245);
  box-shadow: 1px 1px 5px #bdbcbc;
  margin: 10px;
  list-style: none;
  border-radius: 10px;
}

a {
  margin-left: 150px;
  text-decoration: none;
  color: #bf3737;
}

js操作

const btn = document.querySelector('.btn')
const ul = document.querySelector('ul')
const msg_txt = document.querySelector('.msg_txt')
const comment = document.querySelector('.comment')
btn.addEventListener('click', function () {
  let lis = document.createElement('li')
  // 当输入内容为空时显示提示
  if (msg_txt.value === '') {
    alert('输入内容不能为空')
  } else {
    // 不为空的时候显示文字，添加li标签
    lis.innerHTML = `
    ${msg_txt.value}  
    <a href="javascript:;">删除</a>
    `
    ul.appendChild(lis)
  }
  // 复原 原来的文本
  msg_txt.value = ''

  // 删除模块
  const as = document.querySelectorAll('a')
  for (let i = 0; i < as.length; i++) {
    as[i].addEventListener('click', function () {
      this.parentNode.remove()
    })
  }

})