methods 方法之间的传递参数

<div id="app">
      <!-- 双大括号语法文本插值 -->
      {{num}}
      <!-- 传递实参 -->
      <p><button v-on:click="sub(2)">自加</button></p>
</div>
<script src="https://unpkg.com/vue@next"></script>
<script>
        const app = Vue.createApp({
            data(){
              return{
                message:'Vue',
                num:1
              }
            },//方法
            methods:{
                // 传递形参par
                sub:function(par){
                    this.num+=par
                }
            }
        })
        const vm = app.mount('#app')
</script>