![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
Correction status：Uncorrected
Teacher's comments：
Collection
Collection
<!DOCTYPE html>
<html lang="en">
<head>
<style type="text/css">
div:nth-child(1){
width: 450px;
height: 650px;
background-color: lightskyblue;
margin: 30px auto;
color: #333;
box-shadow: 2px 2px 2px #808080;
}
h2{
text-align: center;
margin-bottom: -10px;
}
div:nth-child(2){
width: 400px;
height: 500px;
border: 4px double green;
background-color: #efefef;
margin: 20px auto 10px;
}
ul{
list-style-type: none;
line-height: 2em;
padding: 15px;
overflow: hidden;
}
table{
width: 90%;
height: 80px;
margin: auto;
/*border: 1px solid red;*/
}
td{
/*border: 1px solid red;*/
}
button{
width: 60px;
height: 40px;
background-color: seagreen;
color: #fff;
border: none;
}
button:hover{
cursor: pointer;
background-color: orange;
}
textarea{
/*禁止文本域调整*/
resize: none;
border: none;
background-color: lightyellow;
}
</style>
<meta charset="UTF-8">
<title>在线客服</title>
</head>
<body>
<div class="box">
<h2>在线客服</h2>
<div contenteditable="true">
<ul>
<li></li>
</ul>
</div>
<table>
<td><textarea cols="50" rows="4" name="text"></textarea></td>
<td><button>发送</button></td>
</table>
</div>
<script type="text/javascript">
var inputtext = document.getElementsByName("text")[0];
var btn = document.getElementsByTagName("button")[0];
var list = document.getElementsByTagName("ul")[0];
var sum = 0;
btn.onclick = function () {
if(inputtext.value.length==0){
alert("客观，您想说点什么呢？");
input.focus();
return false;
}
var userComment = inputtext.value;
inputtext.value = "";
var li = document.createElement("li");
var userPic = "<img src='images/peter.jpg' width='30' style='border-radius: 50%'>"
li.innerHTML = userPic+ userComment;
list.appendChild(li);
sum++;
setTimeout(function () {
var info=["好烦人，本姑娘好累","除了不允许退货、退款，什么都可以聊","有事情快说"];
var tmp = info[Math.floor(Math.random()*3)];
var reply = document.createElement("li");
var kefuPic = "<img src='images/zly.jpg' width='30' style='border-radius: 50%'>"
reply.innerHTML = kefuPic+"<span style='color: red'>"+tmp+"</span>";
list.appendChild(reply);
sum++;
},1000);
if(sum>10){
list.innerHTML = "";
}
}
</script>
</body>
</html>Math.random() 生成0到1之间的随机数，但是不会取到0和1
Math.random()*3 生成0到3之间的随机数
Math.floor对一个数取整
document.createElement 创建一个元素
appendChild 添加一个元素
