SOURCE

var btn = {
    template:`<button>组件add</button>`
}
var app = new Vue({
    el:'#app',
    data:{
        count:1
    },
    components:{
        "btn":btn
    },
    methods:{
        add:function(num){
            this.count++;
            if(num!=""){
                this.count+=num;
            }else{
                this.count++;
            }
        }
    }
});

<script src="https://unpkg.com/vue"></script>
<h1>Methods Option</h1>
<hr />
<div id="app">
    <p>{{count}}</p>
    <button @click="add(2)">add</button>
    <p><btn @click.native="add(2)"></btn></p>
</div>
<button onclick="app.add(2)">外部add</button>

*:not(button){
    color:#fff;
}
a:visited{
    color:lightblue
}