SOURCE

const app = new Vue({
    el: "#app",
    methods:{
        btnClick:function(){
            //1.$children是一个数组
            alert(this.$children[0].title)
        },
    },
    components:{
        'my-cpn':{
            template:"#cpn",
            data(){
                return {
                    title:"我是子组件的标题"
                }
            }
        }
    }
})

<div id="app">
	<my-cpn></my-cpn>
    <my-cpn></my-cpn>
    <button @click="btnClick">点击</button>
</div>

<script type="text/x-template" id="cpn">
	<div>
		<h2>{{title}}</h2>
	</div>
</script>