# RouteDefinition

[`createRouter()`](/docs/platform/lwr/references/csr-reference/createrouter.md) takes a [`RouterConfig`](/docs/platform/lwr/references/csr-reference/routerconfig.md) object. `RouterConfig` has to contain an array of `RouteDefinition` objects.

## Syntax

```javascript
interface RouteDefinition<TMetadata = Record<string, any>> {
    id: string;
    uri: string;
    page: Partial<PageReference>
    handler: () => Promise<{ default: RouteHandler }>
    patterns?: { [paramName: string]: string };
    exact?: boolean;
    metadata?: TMetadata;
}
```

## Properties

| Property   | Type    | Required/Optional | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| ---------- | ------- | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `id`       | String  | Required          | Each `RouteDefinition` has to have a unique identifier.                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| `uri`      | String  |                   | A string pattern for URI locations that match this `RouteDefinition`. You can use the following characters: `/`, `:parameter`, `?`, `&`. You can't use `#` or `*`.                                                                                                                                                                                                                                                                                                                          |
| `page`     |         |                   | The form of page references that match the [`LwrConfigRouteDefinition`](/docs/platform/lwr/references/csr-reference/lwrconfigroutedefinition.md). `page` values can be `:parameter` bindings, which map a path or query parameter from the URI to an `attributes` or `state` property, or literal bindings, which hard code a `type`, `attribute`, or `state` property to a literal value. Literal bindings can't contain the following characters: `?`, `*`, `#`, `&`, `+`, `;`, `(`, `)`. |
| `handler`  | String  | Optional          | A promise to a module that's called when a `RouteDefinition` matches a location. For more information, see [Route Handler Modules](https://developer.salesforce.com/docs/platform/lwr/guide/lwr-route-handler-modules.md).                                                                                                                                                                                                                                                                  |
| `patterns` |         | Optional          | A regular expression that a parameter has to match to be valid. To prevent unexpected values in the expression pattern, explicitly wrap the expression in the start-of-line character (`^`) and end-of-line character (`$`). For example: `{"patterns": {"parameter": "^id[0-9a-zA-Z]{5}$"}}`.                                                                                                                                                                                              |
| `exact`    | Boolean | Optional          | If there's a nested router, this value must be `false`. The default value is `true`.                                                                                                                                                                                                                                                                                                                                                                                                        |
| `metadata` |         | Optional          | Developer-defined metadata in the form of key (string) and value (any type) pairs. You can use the `metadata` property to attach additional information to an [`LwrConfigRouteDefinition`](/docs/platform/lwr/references/csr-reference/lwrconfigroutedefinition.md). Extend `LwrConfigRouteDefinition` for required or more strongly typed metadata.                                                                                                                                        |

## Example

```sfdocs-code {"lang":"javascript", "title": "", "src": "" }
{
    id: 'namedPage',
    uri: '/:pageName',
    handler: () => import('example/namedPageHandler'),
    page: {
        type: 'namedPage',
        attributes: {
            pageName: ':pageName',
        },
    },
}
```

**See Also**

- [Routers and Route Matching: Route Definitions](/docs/platform/lwr/guide/lwr-routers-route-matching.html#route-definitions)
- [Create a Router: Configure createRouter()](/docs/platform/lwr/guide/lwr-create-router.html#2-configure-createrouter)
- [Route Handler Modules](/docs/platform/lwr/guide/lwr-route-handler-modules.html#1-the-router-calls-routedefinitionhandler)