Vue2-指令语法-v-on

<button v-on:click="open1">1</button>
<button @click="open2">2</button>
<button @click="open3($event,66)">3</button>

<script>
    new Vue({
        el:"#root",
        methods:{
            open1(){
                console.log("v-on");
            },
            open2(){
                console.log("@");
            },
            open3(event,num){
                console.log(this); //vue对象
                console.log(event); //$event(vue中的标识符)就是这个按钮2
                console.log(num);
            }
        }
    })
</script>