<template>
 <div class="options">
   <div>这里是 options</div>
 </div>
</template>
 
<script>
// @ is an alias to /src
export default {
 name: 'myoptions',
 data(){
   return {}
 },
 created(){  
 },
 mounted(){
  }
}
</script>

<template>
 <div class="select">
   <div>这里是 Select</div>
   <slot></slot>
 </div>
</template>
 
<script>
// @ is an alias to /src
 
 
export default {
 name: "myselect",
 data(){
   return {
     _children:[]
   }
 },
 created(){
   console.log(this.$children) // 输出为 []
   console.log(this.$slots.default) //输出为 [VNode, VNode, VNode]
   var arr = this.$slots.default || []
   var res = [];
   for(var i = 0; i < arr.length; i++){
      var item = arr[i];
      if(item.componentOptions && item.componentOptions.tag == "myOptions"){
        res.push(item);
      }
   }
   this._children = res;
   this.$slots.default = res;
 },
 mounted(){
  console.log(this.$slots.default) //[VNode, VNode]
  console.log(this.$children)//因为过滤掉了一个，所以为 [VueComponent, VueComponent]
 }
}
</script>

this.$slots.default和 this.$children