Sementara computed property cocok untuk kalkulasi sinkron, Watcher digunakan untuk menjalankan efek samping (side effects) saat suatu data berubah.
Konsep Kunci Materi:
- Kapan Menggunakan Watcher: Melakukan request API (HTTP fetch), manipulasi audio/video, atau menyimpan state ke localStorage.
- Parameter Nilai Baru & Lama: Method watcher menerima dua argumen:
(newVal, oldVal). - Opsi
deep & immediate: Memantau mutasi dalam objek bersarang (deep) atau memicu watcher langsung saat komponen pertama kali dimuat (immediate).
<!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 Watchers</span>
<span class="badge-vue">Vue 3 Live</span>
</div>
<p>Pencarian Real-Time (Simulasi API):</p>
<input type="text" v-model="kueriPencarian" placeholder="Ketik kata kunci...">
<div style="margin-top:12px; font-size:13px; color:#64748b;">
Status Watcher: <strong>{{ statusPencarian }}</strong>
</div>
</div>
<script>
const { createApp, ref, reactive, computed, watch, onMounted } = Vue;
createApp({
data() {
return {
kueriPencarian: "",
statusPencarian: "Menunggu masukan ketikan..."
};
},
watch: {
kueriPencarian(nilaiBaru, nilaiLama) {
this.statusPencarian = "Mendeteksi perubahan dari '" + nilaiLama + "' ke '" + nilaiBaru + "'... Mencari data...";
// Simulasi panggilan AJAX asinkron
}
}
}).mount('#app');
</script>
</body>
</html>
Coba Sendiri (Try it Yourself) »