<view class="canlendarBgView">
 <view class="canlendarView">
  <view class="canlendarTopView">
   <view class="leftBgView" bindtap="handleCalendar" data-handle="prev">
    <view class="leftView">《</view>
   </view>
   <view class="centerView">{{cur_year || "--"}} 年 {{cur_month || "--"}} 月</view>
   <view class="rightBgView" bindtap="handleCalendar" data-handle="next">
    <view class="rightView">》</view>
   </view>
  </view>
  <view class="weekBgView">
   <view class="weekView" wx:for="{{weeks_ch}}" wx:key="{{index}}" data-idx="{{index}}">{{item}}</view>
  </view>
  <view class="dateBgView">
   <view wx:if="{{hasEmptyGrid}}" class="dateEmptyView" wx:for="{{empytGrids}}" wx:key="{{index}}" data-idx="{{index}}">
   </view>
   <view class="dateView" wx:for="{{days}}" wx:key="{{index}}" data-idx="{{index}}" bindtap="dateSelectAction">
    <view class="datesView {{index == todayIndex ">{{item}}</view>
   </view>
  </view>
 </view>
 <view>点击日期选择</view>
</view>

//index.js
//获取应用实例
Page({
 data: {
  hasEmptyGrid: false,
  cur_year: '',
  cur_month: '',
 },
 onLoad(options) {
  this.setNowDate();
 },
 
 dateSelectAction: function (e) {
  var cur_day = e.currentTarget.dataset.idx;
  this.setData({
   todayIndex: cur_day
  })
  console.log(`点击的日期:${this.data.cur_year}年${this.data.cur_month}月${cur_day + 1}日`);
 },
 
 setNowDate: function () {
  const date = new Date();
  const cur_year = date.getFullYear();
  const cur_month = date.getMonth() + 1;
  const todayIndex = date.getDate() - 1;
  console.log(`日期：${todayIndex}`)
  const weeks_ch = ['日', '一', '二', '三', '四', '五', '六'];
  this.calculateEmptyGrids(cur_year, cur_month);
  this.calculateDays(cur_year, cur_month);
  this.setData({
   cur_year: cur_year,
   cur_month: cur_month,
   weeks_ch,
   todayIndex,
  })
 },
 
 getThisMonthDays(year, month) {
  return new Date(year, month, 0).getDate();
 },
 getFirstDayOfWeek(year, month) {
  return new Date(Date.UTC(year, month - 1, 1)).getDay();
 },
 calculateEmptyGrids(year, month) {
  const firstDayOfWeek = this.getFirstDayOfWeek(year, month);
  let empytGrids = [];
  if (firstDayOfWeek > 0) {
   for (let i = 0; i < firstDayOfWeek; i++) {
    empytGrids.push(i);
   }
   this.setData({
    hasEmptyGrid: true,
    empytGrids
   });
  } else {
   this.setData({
    hasEmptyGrid: false,
    empytGrids: []
   });
  }
 },
 calculateDays(year, month) {
  let days = [];
 
  const thisMonthDays = this.getThisMonthDays(year, month);
 
  for (let i = 1; i <= thisMonthDays; i++) {
   days.push(i);
  }
 
  this.setData({
   days
  });
 },
 handleCalendar(e) {
  const handle = e.currentTarget.dataset.handle;
  const cur_year = this.data.cur_year;
  const cur_month = this.data.cur_month;
  if (handle === 'prev') {
   let newMonth = cur_month - 1;
   let newYear = cur_year;
   if (newMonth < 1) {
    newYear = cur_year - 1;
    newMonth = 12;
   }
 
   this.calculateDays(newYear, newMonth);
   this.calculateEmptyGrids(newYear, newMonth);
 
   this.setData({
    cur_year: newYear,
    cur_month: newMonth
   })
 
  } else {
   let newMonth = cur_month + 1;
   let newYear = cur_year;
   if (newMonth > 12) {
    newYear = cur_year + 1;
    newMonth = 1;
   }
 
   this.calculateDays(newYear, newMonth);
   this.calculateEmptyGrids(newYear, newMonth);
 
   this.setData({
    cur_year: newYear,
    cur_month: newMonth
   })
  }
 }
})