写一下小程序云开发的，日历挂件的js、wxml、wxss以及相应的增删改查云函数

好的，以下是一个示例的小程序云开发的日历挂件的代码：

1. 日历挂件的 js 文件：

// pages/calendar/calendar.js

const app = getApp()

Page({
  data: {
    currentDate: '', // 当前选中的日期
    events: [], // 日历事件列表
  },

  onLoad: function () {
    this.getCurrentDate()
    this.getEvents()
  },

  getCurrentDate: function () {
    const currentDate = new Date().toLocaleDateString()
    this.setData({
      currentDate: currentDate
    })
  },

  getEvents: function () {
    const db = wx.cloud.database()
    db.collection('events').where({
      date: this.data.currentDate
    }).get().then(res => {
      this.setData({
        events: res.data
      })
    }).catch(err => {
      console.error(err)
    })
  },

  onDateChange: function (e) {
    const currentDate = e.detail.value
    this.setData({
      currentDate: currentDate
    })
    this.getEvents()
  },

  onAddEvent: function () {
    wx.navigateTo({
      url: '/pages/addEvent/addEvent?date=' + this.data.currentDate
    })
  },

  onDeleteEvent: function (e) {
    const eventId = e.currentTarget.dataset.id
    const db = wx.cloud.database()
    db.collection('events').doc(eventId).remove().then(() => {
      this.getEvents()
    }).catch(err => {
      console.error(err)
    })
  }
})

2. 日历挂件的 wxml 文件：

<!-- pages/calendar/calendar.wxml -->

<view class="container">
  <picker mode="date" value="{{currentDate}}" bindchange="onDateChange">
    <view class="date-picker">
      {{currentDate}}
    </view>
  </picker>
  <view class="event-list">
    <block wx:for="{{events}}" wx:key="index">
      <view class="event-item">
        <text>{{item.title}}</text>
        <text>{{item.time}}</text>
        <button data-id="{{item._id}}" bindtap="onDeleteEvent">删除</button>
      </view>
    </block>
  </view>
  <button class="add-button" bindtap="onAddEvent">添加事件</button>
</view>

3. 日历挂件的 wxss 文件：

/* pages/calendar/calendar.wxss */

.container {
  padding: 20px;
}

.date-picker {
  font-size: 18px;
  text-align: center;
}

.event-list {
  margin-top: 20px;
}

.event-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

.add-button {
  width: 100%;
  height: 40px;
  line-height: 40px;
  text-align: center;
  background-color: #007aff;
  color: #fff;
  border-radius: 4px;
}

4. 相应的增删改查云函数：

- 添加事件的云函数：

// cloudfunctions/addEvent/index.js

const cloud = require('wx-server-sdk')

cloud.init()

exports.main = async (event, context) => {
  const db = cloud.database()
  const { title, time, date } = event
  try {
    return await db.collection('events').add({
      data: {
        title: title,
        time: time,
        date: date
      }
    })
  } catch (e) {
    console.error(e)
  }
}

- 删除事件的云函数：

// cloudfunctions/deleteEvent/index.js

const cloud = require('wx-server-sdk')

cloud.init()

exports.main = async (event, context) => {
  const db = cloud.database()
  const { eventId } = event
  try {
    return await db.collection('events').doc(eventId).remove()
  } catch (e) {
    console.error(e)
  }
}

以上是一个小程序云开发的日历挂件的示例代码，包括了日历挂件的前端逻辑和相应的增删改查云函数。请根据自己的实际需求进行修改和扩展。