App.vue
main.js
 
<template>
  <h2>Example data Option</h2>
  <p>Using the 'msg' data property inside the data option to hold a message:</p>
  <pre>{{ msg }}</pre>
</template>

<script>
export default {
  data() {
    return {
      msg: 'Hello World!'
    };
  }
};
</script>

<style>
pre {
  display: inline;
  background-color: lightgreen;
}
</style>                  
import { createApp } from 'vue'

import App from './App.vue'

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