<template>
   <div class="star" :class="starType">
     <span class="star-item" :class="itemClass" v-for="itemClass in itemClasses"></span>
   </div>
 </template>
 <script type="text/ecmascript-6">
   const LENGTH=5;
   const CLS_ON="on";
   const CLS_OFF="off";
   const CLS_HALF="half";
  export default {
     props:{
       size:{
         type:Number
       },
       score:{
         type:Number
       }
     },
     computed:{
       starType(){
         return "star-"+this.size;
       },
       itemClasses(){
         //计算属性
        let result=[];
         let score=Math.floor(this.score*2)/2;
         let hasDecimal=score%1!==0; //是否有效数
        let integer=Math.floor(score);//取整
        for (var i = 0; i < integer; i++) {
           result.push(CLS_ON);
         }
         if (hasDecimal) {
           //有且最多一个半星
          result.push(CLS_HALF);
         }
         while(result.length<LENGTH){
           result.push(CLS_OFF);
         }
         //数组填充完毕
        return result;
       }
     }
   };
 </script>
 <style lang="stylus" ref="sheetstyle/stylus">
   @import "../../common/stylus/mixin.styl";
   .star
     font-size:0
     .star-item
       display:inline-block
       background-repeat:no-repeat
     &.star-48
       .star-item
         width:20px
         height:20px
         margin-right:22px
         background-size:20px 20px
         &:last-child
           margin-right:0
         &.on
           bg-image('star48_on')
         &.half
           bg-image('star48_half')
         &.off
           bg-image('star48_off')
     &.star-36
       .star-item
         width:15px
         height:15px
         margin-right:6px
         background-size:15px 15px
         &:last-child
           margin-right:0
         &.on
           bg-image('star36_on')
         &.half
           bg-image('star36_half')
         &.off
           bg-image('star36_off')
     &.star-24
       .star-item
         width:10px
         height:10px
         margin-right:3px
         background-size:10px 10px
         &:last-child
           margin-right:0
         &.on
           bg-image('star24_on')
         &.half
           bg-image('star24_half')
         &.off
           bg-image('star24_off')  
 </style>

bg-image($url)
   background-image:url($url+"@2x.png")
   @media (-webkit-min-device-pixel-ratio:3),(min-device-pixel-ratio:3)
     background-image:url($url+"@3x.png")

<star :size="48" :score="3.5"></star>