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

# Type Alias: TransitionCallbackReason

```ts
type TransitionCallbackReason = TransitionEventType | "hostConnected";
```

Defined in: [packages/lit-ui-router/src/transition-controller.ts:42](https://github.com/simshanith/lit-ui-router/blob/740888c2b2ba358c4dfa52a122e927df6a604b12/packages/lit-ui-router/src/transition-controller.ts#L42)

The reason a [TransitionController](TransitionController.md) invoked its callback.

Either one of the observed [TransitionEventType](TransitionEventType.md) hooks fired, or the
host element (re)connected to the DOM and the controller synchronized
with the router's current state (`'hostConnected'`).