js案例（论坛发帖效果的实现）
<!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>
* {
margin: 0;
padding: 0;
}
ul {
list-style: none;
}
#send {
width: 150px;
line-height: 40px;
background-color: #009966;
color: #fff;
font-size: 18px;
text-align: center;
border-radius: 10px;
margin-bottom: 5px;
}
.wrapper {
width: 500px;
margin: 10px auto;
}
.form {
width: 500px;
background-color: white;
border: 1px solid lightgray;
position: absolute;
display: none;
}
.form>div {
margin: 10px;
}
#sub {
width: 120px;
line-height: 25px;
border-radius: 5px;
background-color: #009966;
text-align: center;
color: #fff;
font-weight: bold;
font-size: 14px;
}
ul {
border-top: 1px solid lightgray;
}
ul>li {
display: flex;
color: lightgray;
font-size: 12px;
border-bottom: 1px dashed lightgray;
height: 60px;
margin-top: 10px;
}
ul>li img {
width: 50px;
border-radius: 50%;
}
.bk {
margin-left: 20px;
}
.bk h4 {
color: black;
font-size: 14px;
line-height: 30px;
}
input {
width: 450px;
line-height: 30px;
}
</style>
</head>
<body>
<div class="wrapper">
<div id="send">我要发帖</div>
<div class="form">
<div><input type="text" placeholder="请输入标题（1-50个字符）"></div>
<div>所属板框：
<select name="" id="se">
<option value="">请选择板块</option>
<option value="">电子书籍</option>
<option value="">新课来了</option>
<option value="">新手报到</option>
<option value="">职业规划</option>
</select>
</div>
<div class="text">
<textarea name="" id="" cols="62" rows="15">
</textarea>
<div id="sub">发布</div>
</div>
</div>
<ul>
<!-- 模板样式 -->
<!-- <li>
<div><img src="./img/tou01.jpg" alt=""></div>
<div class="bk">
<h4>888</h4>
<p>板块:<span id="bk">新手报到</span>   发表时间：<span id="time">1111</span></p>
</div>
</li> -->
</ul>
</div>
<script>
var _send = document.getElementById("send");//获取我要发帖节点
// console.log(send)
var _form = document.querySelector(".form");//获取发帖内容节点
// console.log(_form)
//点击事件
_send.onclick = function () {
// this.style.display="block";
_form.style.display = "block"//点击form节点出现
_input.value = ""
}
var _sub = document.querySelector("#sub");//获取发布节点
var _ul = document.querySelector("ul");//获取ul节点
var _input = document.querySelector("input");//获取input节点
//点击发布
_sub.onclick = function () {
var title = _input.value; //获取input的值
if (title == "") {
alert("请输入标题")
} else {
_form.style.display = "none"//form节点隐藏
var _li = document.createElement("li");//新增li节点
var _div1 = document.createElement("div");//新增div节点
var _img = document.createElement("img");//新增img节点
var _random = Math.floor(Math.random() * 4);//生成随机数作为图片数组的下标
var _images = ["./img/tou01.jpg", "./img/tou02.jpg", "./img/tou03.jpg", "./img/tou04.jpg"];//图片数组
var _imgSrc = _images[_random];//生成随机图片效果
_img.src = _imgSrc;
_li.append(_div1);//div增加到li标签中
_div1.append(_img);//img加到div中
/***************************/
var _div2 = document.createElement("div");//新增div
_div2.setAttribute("class", "bk");//给div添加class属性
var _h4 = document.createElement("h4");//新增h4标签
_h4.innerText = title;//input的值放入到h4标签中
_li.append(_div2);//div加入到li标签中
_div2.append(_h4);//h4加入到div标签中
/*******************************/
var _p = document.createElement("p");//新增一个p标签；
//给p标签加内容
_p.innerHTML = `板块:<span id="bk">${
Select()}</span>   发表时间：<span id="time">${
sendTime()}</span>`;
_div2.append(_p);//p标签加入到div中
//把完整的li插入到ul的第一个孩子前面
_ul.insertBefore(_li, _ul.firstElementChild);
}
}
//获取当前时间
function sendTime() {
var _time = new Date();
var years = _time.getFullYear();
var months = _time.getMonth()+1;
var date = _time.getDate();
var hours = _time.getHours();
var minutes = _time.getMinutes();
// console.log(`${years}-${months}-${date} ${hours}:${minutes}`);
return `${
years}-${
months}-${
date} ${
hours}:${
minutes}`;
}
// sendTime();
var _select = document.querySelector("select");
//切换事件
_select.onchange = function () {
Select();
}
//获取下拉框的值
function Select() {
//获取当前选中的option的下标
var selectIndex = _select.selectedIndex;
// console.log(selectIndex);
//获取select下所有options
var options = _select.options;
//获取当前选中的option的文本值
console.log(options[selectIndex].innerText);
return options[selectIndex].innerText;
}
</script>
</body>
</html>
效果图：
