createApp() Create an App Instance
Last updated: 2026-10-22
createApp() Create an App Instance
createApp() creates an app instance from the root component; the returned object registers components, installs plugins and mounts.
| Group | Global API |
|---|---|
| Kind | API |
| Scope | Global |
| Vue Version | 3.0+ |
| SSR Support | Yes |
📝 Syntax
const app = createApp(App)
app.use(router)
app.mount("#app")⚙️ Arguments
| rootComponent, rootProps? | The root component definition (optionally root props) |
|---|
Returns：An app instance with mount, component, use, provide and config
▶ Example
Edit the code below and see the live result:
Output：
Shows 'app running'.💡 Key Points
💡 Tip The app instance differs from the root component instance.
ℹ️ Note Multiple apps can coexist, fully isolated.
⚠️ Warning Configure before mounting — later registrations do not apply.
🏷️ Related Global API
💡 Related Cases
More case studies coming soon.
📚 Related Tutorials
❓ FAQ
Q How is it different from new Vue()?
A Vue 3 uses a factory for isolated app instances.
Q Can it mount several roots?
A One root per app — create more apps if needed.
Q What if I never mount?
A Nothing renders until mount is called.
