<button @click="countUp">+1</button>
 or
<button @click="countUp()">+1</button>
🙅‍♂️
<p>{{ doubleCounterMethod }} </p>

🙆‍♂️
<p>{{ doubleCounterMethod() }} </p>
<!DOCTYPE html>
<html lang="ja">
<head>
    <script src="<https://unpkg.com/[email protected]>"></script>
</head>
<body>
    <div id="app">
        <button v-on:click="onClick">Click!</button>
        <p>{{ now }}</p>

    </div>

    <script>
        const app = Vue.createApp({
            data: () => ({
                now: '-'
            }),
            methods: {
                onClick: function(){
                    this.now = new Date().toLocaleString()
                }
            }
        })
        app.mount('#app')

    </script>
</body>
</html>
<button @[event]="countUp">カウントアップ</button>

キー修飾子

<input type="text" @keyup.enter.space="myAlert">
🔼スペースやエンターを押した時に、メソッド動く
new Vue({
    el: "#app",
    data: {
        number: 0,
        event: 'click'
    },
    methods: {
        countUp() {
            this.number += 1
        }
    }
});
<input type="text" @keyup="myAlert">

.space