jquery实现简单每周轮换的日历

<div id="app">
 <div class="title"></div>
 <div class="left"><</div>
 <ul>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
 </ul>
 <div class="right">></div>
</div>

<style>
 #app {
  width: 400px;
  height: 50px;
  margin: 200px auto;
  position: relative;
  color: darkgray;
 }
 .title {
  position: absolute;
  top: -50px;
  left: 0;
  width: 200px;
  height: 50px;
 }
 ul {
  list-style: none;
  background-color: blanchedalmond;
  width: 100%;
  display: block;
  padding: 0;
 }
 ul li {
  display: inline-block;
  width: 50px;
  height: 50px;
  text-align: center;
  line-height: 50px;
  cursor: pointer;
 }
 .left {
  position: absolute;
  top: 0;
  left: -50px;
  font-size: 35px;
  cursor: pointer;
 }
 .right {
  position: absolute;
  top: 0;
  right: -50px;
  font-size: 35px;
  cursor: pointer;
 }
 .on {
  color: darkorange;
 }
</style>

<script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
 <script>
 let now = new Date()
 let oneDay = 1000*60*60*24 // 一天的时间
 let timeArr = [] // 用来存储每次循环真正时间戳的数组
 let onDate = now.getTime() // 当前激活的日期（有且仅有一个）
 init()
 // 点击后添加激活样式
 $('ul li').on('click', function() {
  acton($(this).index())
 })
 $('.left').on('click', function() {
  changeUl(0)
 })
 $('.right').on('click', function() {
  changeUl(1)
 })

 function init() {
  // 计算初始化时的周一和周天
  let monday = now.getTime() - (now.getDay() - 1)*oneDay
  let sunday = now.getTime() + (7 - now.getDay())*oneDay
  // 循环渲染本周
  for(let i = 0;i < 7;i++) {
  let nowDate = monday + oneDay * i
  $('ul li').eq(i).text(new Date(nowDate).getDate())
  timeArr.push(nowDate)
  if (nowDate === now.getTime()) { // 初始化时渲染标签并激活当前本地日期和显示
   acton(i)
  }
  }
 }
 
 // 判断数组中是否存在该日期并激活
 function judon() {
  if (timeArr.indexOf(onDate) !== -1) {
  $('ul li').eq(timeArr.indexOf(onDate)).addClass('on').siblings().removeClass('on')
  } else {
  $('ul li').each(function() {
   $(this).removeClass('on')
  })
  }
 }

 // 点击前后实现更换每周内容,1是前进一周,0是后退一周
 function changeUl(type) {
  for (let n = 0;n < 7;n++) {
  timeArr[n] = type ? timeArr[n] + oneDay*7 : timeArr[n] - oneDay*7
  $('ul li').eq(n).text(new Date(timeArr[n]).getDate())
  }
  judon()
 }
 
 // 激活日期并显示
 function acton(i) {
  let nowTitle = new Date(timeArr[i]);
  $('ul li').eq(i).addClass('on').siblings().removeClass('on');
  $('.title').text(`${nowTitle.getFullYear()}年${nowTitle.getMonth()+1}月${nowTitle.getDate()}日`);
  onDate = timeArr[i]
 }
</script>