---
url: >-
  https://lit-ui-router.dev/reference/lit-ui-router-ssr/index/functions/registerTraceCategory.md
---
[lit-ui-router-ssr](../../index.md) / [lit-ui-router-ssr](../index.md) / registerTraceCategory

# Function: registerTraceCategory()

```ts
function registerTraceCategory(router, name): void;
```

Defined in: [packages/lit-ui-router-ssr/src/trace-categories.ts:123](https://github.com/simshanith/lit-ui-router/blob/1a559af0dc04d61d71ea4536fe2398902475b4ce/packages/lit-ui-router-ssr/src/trace-categories.ts#L123)

Registers a trace category beyond core's fixed set, so
`router.trace.enable(name)`, `disable(name)` and `enabled(name)` switch it
alone, and a no-argument `enable()` or `disable()` covers it too.

Core normalizes every category name through its `Category` enum, so on its
own an unknown name lands on one shared `undefined` key, and enabling any
unknown name reads every other as enabled. This installs, once per router,
a wrapper over `router.trace` that answers registered names itself and
forwards everything else to core's trace. Core's own code logs through the
imported `trace` singleton, which the wrapper leaves untouched. Registered
names are kept per underlying trace, so every router registered over core's
singleton agrees on them; a router that never registers reads core's trace
unwrapped, and core's imported `trace.disable()` leaves registered names on.

When `router.trace` has a `registerCategory` of its own, this delegates to
it and installs nothing.

Register before enabling: call it right after creating the router.

## Parameters

| Parameter | Type | Description |
| ------ | ------ | ------ |
| `router` | [`UIRouter`](https://ui-router.github.io/core/docs/latest/classes/_router_.uirouter.html) | the router whose `trace` gains the category |
| `name` | `string` | the category's name, such as `'HYDRATION'` |

## Returns

`void`

## Throws

an `Error` for one of core's own category names, such as `'TRANSITION'`

## Example

```ts
import { UIRouterLit } from 'lit-ui-router';
import { registerTraceCategory } from 'lit-ui-router-ssr/client';

const router = new UIRouterLit();
registerTraceCategory(router, 'HYDRATION');
router.trace.enable('HYDRATION');
```