小程序如何实现星级评分效果？

<view >      <block wx:for="{{stars}}">      <image class="star-image" style="left: {{item*100}}rpx" src="{{key > item ?(key-item == 0.5?halfSrc:selectedSrc) : normalSrc}}">        <view class="item" style="left:0rpx" data-key="{{item+0.5}}" bindtap="selectLeft"></view>        <view class="item" style="left:50rpx" data-key="{{item+1}}" bindtap="selectRight"></view>      </image>    </block>  <view style="margin-top:450rpx">    <button bindtap="startRating">确认</button>  </view></view>

.star-image{  position: absolute;  top: 50rpx;  margin-left: 100rpx;  width: 100rpx;  height: 100rpx;  src: "/images/icon/star-no.png";}.item{  position: absolute;  top: 50rpx;  width: 100rpx;  height: 100rpx;}

//index.jsvar app = getApp()var count = 0;Page({  data: {    stars: [0, 1, 2, 3, 4],    normalSrc: '/images/icon/star-no.png',    selectedSrc: '/images/icon/star-full.png',    halfSrc: '/images/icon/star-half.png',    key: 0,//评分    status:'',    //0未课评 1已课评  },  /**     * 生命周期函数--监听页面加载     */  onLoad: function (options) {    console.log(options.status)  },  /**   * 点击左边,半颗星   */  selectLeft: function (e) {    var key = e.currentTarget.dataset.key    if (this.data.key == 0.5 && e.currentTarget.dataset.key == 0.5) {      //只有一颗星的时候,再次点击,变为0颗      key = 0;    }    count = key    this.setData({      key: key    })  },  /**   * 点击右边,整颗星   */  selectRight: function (e) {    var key = e.currentTarget.dataset.key    count = key    this.setData({      key: key    })  },  // 确定按钮  startRating: function (e) {    wx.showModal({      title: '分数',      content: "" + count,      success: function (res) {        if (res.confirm) {          console.log('用户点击确定')        }      }    })  }})