vm.$on( event, callback )

vm.$emit( event, […args] )

//父组件
<template>
  <ratingselect @select-type="onSelectType"></ratingselect>
</template>
<script>
  data () {
   return {
    selectType: 0,
  },
  methods: {
   onSelectType (type) {
    this.selectType = type
   }
  }
</script>

// 子组件
<template>
 <div>
  <span @click="select(0, $event)" :class="{'active': selectType===0}"></span>
  <span @click="select(1, $event)" :class="{'active': selectType===1}"></span>
  <span @click="select(2, $event)" :class="{'active': selectType===2}"></span>
 </div>
</template>
<script>
  data () {
   return {
    selectType: 0,
  },
  methods: {
    select (type, event) {
      this.selectType = type
      this.$emit('select-type', type)
   }
  }
</script>