How do you use JavaScript expressions in Vue.js templates?

Any single JavaScript expression placed inside double curly braces {{ }} is evaluated and its result rendered into the page.

<div id="app">
  <p>Hallo {{ vorname + " " + name }}</p>
  <p>{{ "Items: " + warenkorb.length }}</p>
</div>
<script>
Vue.createApp({
  data() { return {
    vorname: "Fritz",
    name: "Muller",
    warenkorb: ["Art1", "Art2", "Art3"]
  }}
}).mount('#app');
</script>

You can use string concatenation, array methods, math operations, etc.