Options: Lifecycle#

:::info See also For shared usage of lifecycle hooks, see Guide - Lifecycle Hooks :::

beforeCreate#

Called when the instance is initialized.

• Type

ts interface ComponentOptions { beforeCreate?(this: ComponentPublicInstance): void }

• Details

Called immediately when the instance is initialized and props are resolved.

Then the props will be defined as reactive properties and the state such as data() or computed will be set up.

Note that the setup() hook of Composition API is called before any Options API hooks, even beforeCreate().

created#

Called after the instance has finished processing all state-related options.

• Type

ts interface ComponentOptions { created?(this: ComponentPublicInstance): void }

• Details

When this hook is called, the following have been set up: reactive data, computed properties, methods, and watchers. However, the mounting phase has not been started, and the $el property will not be available yet.

beforeMount#

Called right before the component is to be mounted.

• Type

ts interface ComponentOptions { beforeMount?(this: ComponentPublicInstance): void }

• Details

When this hook is called, the component has finished setting up its reactive state, but no DOM nodes have been created yet. It is about to execute its DOM render effect for the first time.

This hook is not called during server-side rendering.

mounted#

Called after the component has been mounted.

• Type

ts interface ComponentOptions { mounted?(this: ComponentPublicInstance): void }

• Details

A component is considered mounted after:

• All of its synchronous child components have been mounted (does not include async components or components inside <Suspense> trees).

• Its own DOM tree has been created and inserted into the parent container. Note it only guarantees that the component's DOM tree is in-document if the application's root container is also in-document.

This hook is typically used for performing side effects that need access to the component's rendered DOM, or for limiting DOM-related code to the client in a server-rendered application.

This hook is not called during server-side rendering.

beforeUpdate#

Called right before the component is about to update its DOM tree due to a reactive state change.

• Type

ts interface ComponentOptions { beforeUpdate?(this: ComponentPublicInstance): void }

• Details

This hook can be used to access the DOM state before Vue updates the DOM. It is also safe to modify component state inside this hook.

This hook is not called during server-side rendering.

updated#

Called after the component has updated its DOM tree due to a reactive state change.

• Type

ts interface ComponentOptions { updated?(this: ComponentPublicInstance): void }

• Details

A parent component's updated hook is called after that of its child components.

This hook is called after any DOM update of the component, which can be caused by different state changes. If you need to access the updated DOM after a specific state change, use nextTick() instead.

This hook is not called during server-side rendering.

:::warning Do not mutate component state in the updated hook - this will likely lead to an infinite update loop! :::

beforeUnmount#

Called right before a component instance is to be unmounted.

• Type

ts interface ComponentOptions { beforeUnmount?(this: ComponentPublicInstance): void }

• Details

When this hook is called, the component instance is still fully functional.

This hook is not called during server-side rendering.

unmounted#

Called after the component has been unmounted.

• Type

ts interface ComponentOptions { unmounted?(this: ComponentPublicInstance): void }

• Details

A component is considered unmounted after:

• All of its child components have been unmounted.

• All of its associated reactive effects (render effect and computed / watchers created during setup()) have been stopped.

Use this hook to clean up manually created side effects such as timers, DOM event listeners or server connections.

This hook is not called during server-side rendering.

errorCaptured#

Called when an error propagating from a descendant component has been captured.

• Type

ts interface ComponentOptions { errorCaptured?( this: ComponentPublicInstance, err: unknown, instance: ComponentPublicInstance | null, info: string ): boolean | void }

• Details

Errors can be captured from the following sources:

• Component renders
• Event handlers
• Lifecycle hooks
• setup() function
• Watchers
• Custom directive hooks
• Transition hooks

The hook receives three arguments: the error, the component instance that triggered the error, and an information string specifying the error source type.

:::tip In production, the 3rd argument (info) will be a shortened code instead of the full information string. You can find the code to string mapping in the Production Error Code Reference. :::

You can modify component state in errorCaptured() to display an error state to the user. However, it is important that the error state should not render the original content that caused the error; otherwise the component will be thrown into an infinite render loop.

The hook can return false to stop the error from propagating further. See error propagation details below.

Error Propagation Rules

• By default, all errors are still sent to the application-level app.config.errorHandler if it is defined, so that these errors can still be reported to an analytics service in a single place.

• If multiple errorCaptured hooks exist on a component's inheritance chain or parent chain, all of them will be invoked on the same error, in the order of bottom to top. This is similar to the bubbling mechanism of native DOM events.

• If the errorCaptured hook itself throws an error, both this error and the original captured error are sent to app.config.errorHandler.

• An errorCaptured hook can return false to prevent the error from propagating further. This is essentially saying "this error has been handled and should be ignored." It will prevent any additional errorCaptured hooks or app.config.errorHandler from being invoked for this error.

Error Capturing Caveats

• In components with async setup() function (with top-level await) Vue will always try to render component template, even if setup() threw error. This will likely cause more errors because during render component's template might try to access non-existing properties of failed setup() context. When capturing errors in such components, be ready to handle errors from both failed async setup() (they will always come first) and failed render process.

• Replacing errored child component in parent component deep inside <Suspense> will cause hydration mismatches in SSR. Instead, try to separate logic that can possibly throw from child setup() into separate function and execute it in the parent component's setup(), where you can safely try/catch the execution process and make replacement if needed before rendering the actual child component.

renderTracked ^#

Called when a reactive dependency has been tracked by the component's render effect.

This hook is development-mode-only and not called during server-side rendering.

• Type

```ts interface ComponentOptions { renderTracked?(this: ComponentPublicInstance, e: DebuggerEvent): void }

type DebuggerEvent = { effect: ReactiveEffect target: object type: TrackOpTypes / 'get' | 'has' | 'iterate' / key: any } ```

• See also Reactivity in Depth

renderTriggered <sup>#</sup>

Called when a reactive dependency triggers the component's render effect to be re-run.

This hook is development-mode-only and not called during server-side rendering.

• Type

```ts interface ComponentOptions { renderTriggered?(this: ComponentPublicInstance, e: DebuggerEvent): void }

type DebuggerEvent = { effect: ReactiveEffect target: object type: TriggerOpTypes / 'set' | 'add' | 'delete' | 'clear' / key: any newValue?: any oldValue?: any oldTarget?: Map | Set } ```

• See also Reactivity in Depth

activated#

Called after the component instance is inserted into the DOM as part of a tree cached by <KeepAlive>.

This hook is not called during server-side rendering.

• Type

ts interface ComponentOptions { activated?(this: ComponentPublicInstance): void }

• See also Guide - Lifecycle of Cached Instance

deactivated#

Called after the component instance is removed from the DOM as part of a tree cached by <KeepAlive>.

This hook is not called during server-side rendering.

• Type

ts interface ComponentOptions { deactivated?(this: ComponentPublicInstance): void }

• See also Guide - Lifecycle of Cached Instance

serverPrefetch <sup>#</sup>

Async function to be resolved before the component instance is to be rendered on the server.

• Type

ts interface ComponentOptions { serverPrefetch?(this: ComponentPublicInstance): Promise<any> }

• Details

If the hook returns a Promise, the server renderer will wait until the Promise is resolved before rendering the component.

This hook is only called during server-side rendering can be used to perform server-only data fetching.

• Example

js export default { data() { return { data: null } }, async serverPrefetch() { // component is rendered as part of the initial request // pre-fetch data on server as it is faster than on the client this.data = await fetchOnServer(/* ... */) }, async mounted() { if (!this.data) { // if data is null on mount, it means the component // is dynamically rendered on the client. Perform a // client-side fetch instead. this.data = await fetchOnClient(/* ... */) } } }

• See also Server-Side Rendering