Vue Event Modifiers

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
    <style>
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            background: #f8fafc;
            color: #1e293b;
            padding: 24px;
            margin: 0;
            line-height: 1.6;
        }
        .vue-app-container {
            background: white;
            border-radius: 12px;
            padding: 24px;
            max-width: 520px;
            margin: 0 auto;
            box-shadow: 0 4px 15px rgba(0,0,0,0.06);
            border-top: 4px solid #42b883;
        }
        .vue-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 18px;
            padding-bottom: 12px;
            border-bottom: 1px solid #f1f5f9;
        }
        .vue-title {
            font-weight: 700;
            color: #0d2e5c;
            font-size: 16px;
            display: flex;
            align-items: center;
            gap: 8px;
        }
        .badge-vue {
            background: #42b883;
            color: white;
            padding: 3px 10px;
            border-radius: 20px;
            font-size: 11px;
            font-weight: 700;
        }
        button {
            background: #42b883;
            color: white;
            border: none;
            padding: 8px 16px;
            border-radius: 6px;
            cursor: pointer;
            font-weight: 600;
            font-size: 13px;
            transition: all 0.2s;
        }
        button:hover {
            background: #33a06f;
        }
        input, select, textarea {
            padding: 8px 12px;
            border: 1px solid #cbd5e1;
            border-radius: 6px;
            font-size: 14px;
            box-sizing: border-box;
            outline: none;
        }
        input:focus, select:focus, textarea:focus {
            border-color: #42b883;
            box-shadow: 0 0 0 3px rgba(66, 184, 131, 0.15);
        }
        .pill {
            display: inline-block;
            background: #e2e8f0;
            padding: 4px 10px;
            border-radius: 12px;
            font-size: 12px;
            margin: 2px;
        }
        
    </style>
</head>
<body>
    <div id="app" class="vue-app-container">
        <div class="vue-header">
            <span class="vue-title">🟢 Vue Event Modifiers</span>
            <span class="badge-vue">Vue 3 Live</span>
        </div>
        <!-- .prevent menghentikan reload submit form -->
<form @submit.prevent="kirimForm">
    <p style="margin:0 0 8px 0; font-size:13px;">Ketik dan tekan <strong>ENTER (.enter)</strong>:</p>
    <input type="text" v-model="teksInput" @keyup.enter="kirimForm" placeholder="Tulis catatan..." style="width:100%;">
    <div style="margin-top:10px;">
        <button type="submit">Kirim (.prevent)</button>
        <!-- .once hanya menjalankan handler satu kali -->
        <button type="button" @click.once="hanyaSekali" style="background:#6366f1; margin-left:6px;">
            Klik Sekali Saja (.once)
        </button>
    </div>
</form>
<p style="color:#0284c7; font-size:13px; margin-top:10px;">{{ notifikasi }}</p>
    </div>

    <script>
        const { createApp, ref, reactive, computed, watch, onMounted } = Vue;
        createApp({
    data() {
        return {
            teksInput: "",
            notifikasi: "Menunggu aksi formulir..."
        };
    },
    methods: {
        kirimForm() {
            if (!this.teksInput) return;
            this.notifikasi = "Form berhasil dikirim tanpa reload: '" + this.teksInput + "'";
            this.teksInput = "";
        },
        hanyaSekali() {
            alert("Tombol ini hanya aktif satu kali berkat modifier .once!");
        }
    }
}).mount('#app');
    </script>
</body>
</html>