App.vue
main.js
 
<template>
  <h2>Example $watch() Method</h2>
  <p>Drag the slider to see the watcher work, click the stop button, and drag the slider again to confirm that the watcher has now stopped.</p>
  <div>
    <p><input type="range" min="0" max="10" v-model="value"> Current value: {{ value }}</p>
    <button v-on:click="stopFunc">Stop Watcher</button>
    <ol>
      <li v-for="x in results">{{ x }}</li>
    </ol>
  </div>
</template>

<script>
export default {
  data() {
    return {
      value: 4,
      results: [],
      stopFunc: null
    };
  },
  mounted() {
    this.stopFunc = this.$watch('value', function() {
      this.results.push('$watch() method')
    })
  }
};
</script>

<style scoped>
div {
  border: solid black 1px;
  padding: 10px;
}
</style>                  
import { createApp } from 'vue'

import App from './App.vue'

const app = createApp(App)
app.mount('#app')
                  
http://localhost:5173/