SOURCE

const HelloVueApp = {
  data() {
    return {
      message: "Hello Vue!!"
    };
  }
};
console.log(1, Vue);

Vue.createApp(HelloVueApp).mount("#hello-vue");

<div id="hello-vue" class="demo">
  {{ message }}
</div>

.demo {
  font-family: sans-serif;
  border: 1px solid #eee;
  border-radius: 2px;
  padding: 20px 30px;
  margin-top: 1em;
  margin-bottom: 40px;
  user-select: none;
  overflow-x: auto;
}