div class="star" style="float: right" >
  <span v-for="(itemClass,index) in y.itemClasses" :class="itemClass" data="1" class="star-item" :track-by="index" ></span>
</div>

遍歷資料並重新賦值

let list = response.data.data.data;
that.url = http;

list.forEach(item=>{
  item.itemClasses 
 
= that.itemClasses(item.certificate_level)
});

methods:{
  itemClasses(score_){
    score_ = typeof score_ === 'number'?score_:Number(score_);
    // this.score>5 ? this.score=5 : this.score;
    score_ = score_>=5 ? 5 : score_;
    let result = [];
    let  score =Math.floor(score_ * 2) / 2
 
;
    let hasDecimal = score % 1 !==0;
    let integer = Math.floor(score);
    for(let i=0;i<integer;i++){
      result.push("on");
    }
    if(hasDecimal){
      result.push("half");
    }
    while(result.length <5){
      result.push("off");
    }
    return result;

},

樣式

.star-item
 
{
  display: inline-block;
  background-repeat:no-repeat ;
  width: 0.09rem;
  height: 0.09rem;
  /*margin-right: 0.rem;*/
  background-size:100% ;
}
.star-item.on{
  background-image: url("../../images/_20171226164030.png");
}

.star-item.half{
  background-image: url("../../images/0171226164041.png");
}
.star-item.off{
  background-image: url("../../images/171226164044.png");
}