Add types to NavigationTarget (#14167)

* fix #14048

* Create four-suns-refuse.md

* Apply suggestions from code review

* regenerate

---------

Co-authored-by: Rich Harris <[email protected]>
Co-authored-by: Rich Harris <[email protected]>

Author: MathiasWP

.changeset/four-suns-refuse.md

@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": feat
+---
+
+feat: add `RouteId` and `RouteParams` to NavigationTarget interface

packages/kit/src/exports/public.d.ts

@@ -1020,20 +1020,23 @@ export interface NavigationEvent<
 /**
  * Information about the target of a specific navigation.
  */
-export interface NavigationTarget {
+export interface NavigationTarget<
+	Params extends AppLayoutParams<'/'> = AppLayoutParams<'/'>,
+	RouteId extends AppRouteId | null = AppRouteId | null
+> {
 	/**
 	 * Parameters of the target page - e.g. for a route like `/blog/[slug]`, a `{ slug: string }` object.
 	 * Is `null` if the target is not part of the SvelteKit app (could not be resolved to a route).
 	 */
-	params: Record<string, string> | null;
+	params: Params | null;
 	/**
 	 * Info about the target route
 	 */
 	route: {
 		/**
 		 * The ID of the current route - e.g. for `src/routes/blog/[slug]`, it would be `/blog/[slug]`. It is `null` when no route is matched.
 		 */
-		id: string | null;
+		id: RouteId | null;
 	};
 	/**
 	 * The URL that is navigated to

packages/kit/types/index.d.ts

@@ -997,20 +997,23 @@ declare module '@sveltejs/kit' {
 	/**
 	 * Information about the target of a specific navigation.
 	 */
-	export interface NavigationTarget {
+	export interface NavigationTarget<
+		Params extends AppLayoutParams<'/'> = AppLayoutParams<'/'>,
+		RouteId extends AppRouteId | null = AppRouteId | null
+	> {
 		/**
 		 * Parameters of the target page - e.g. for a route like `/blog/[slug]`, a `{ slug: string }` object.
 		 * Is `null` if the target is not part of the SvelteKit app (could not be resolved to a route).
 		 */
-		params: Record<string, string> | null;
+		params: Params | null;
 		/**
 		 * Info about the target route
 		 */
 		route: {
 			/**
 			 * The ID of the current route - e.g. for `src/routes/blog/[slug]`, it would be `/blog/[slug]`. It is `null` when no route is matched.
 			 */
-			id: string | null;
+			id: RouteId | null;
 		};
 		/**
 		 * The URL that is navigated to