---
url: >-
  https://lit-ui-router.dev/reference/lit-ui-router/controllers/TransitionEventType.md
---
[lit-ui-router](../index.md) / TransitionEventType

# Type Alias: TransitionEventType

```ts
type TransitionEventType = "onBefore" | "onStart" | "onSuccess" | "onError";
```

Defined in: [packages/lit-ui-router/src/transition-controller.ts:27](https://github.com/simshanith/lit-ui-router/blob/740888c2b2ba358c4dfa52a122e927df6a604b12/packages/lit-ui-router/src/transition-controller.ts#L27)

Transition lifecycle events that a [TransitionController](TransitionController.md) can observe.

Each value corresponds to a
[TransitionService hook registry](https://ui-router.github.io/core/docs/latest/interfaces/_transition_interface_.ihookregistry.html)
method of the same name.