通过@hook:mounted 子组件mounted之后，会调用此函数。这个函数中可以通过ref调该子组件。
<template>
<div>
<WQuery @hook:mounted="childMounted"></WQuery>
</div>
</template>
<script>
import coms from "@/components/async.js";
export default {
mounted() {
console.log(this.$refs.form);
},
components: {
...coms
},
methods: {
childMounted () {
alert('childMounted')
},
},
};
</script>
