How do you create and mount a Vue.js application?

You pass a config object with a data() function to Vue.createApp(), then attach it to the page with .mount() and a CSS selector.

<div id="msg">
  <p>{{ message }}</p>
</div>
<script>
Vue.createApp({
  data() {
    return {
      message: "Hello World"
    }
  }
}).mount('#msg');
</script>

The data() function returns an object whose properties become available in the template.