docs: add typed routes

Author: posva

packages/docs/.vitepress/config.ts

@@ -174,6 +174,10 @@ const config = defineConfig({
                 text: 'Lazy Loading Routes',
                 link: '/guide/advanced/lazy-loading.html',
               },
+              {
+                text: 'Typed Routes',
+                link: '/guide/advanced/typed-routes.html',
+              },
               {
                 text: 'Extending RouterLink',
                 link: '/guide/advanced/extending-router-link.html',

packages/docs/guide/advanced/typed-routes.md

@@ -0,0 +1,70 @@
+# Typed routes (v4.1.0+)
+
+> ⚠️ This feature is still experimental and will evolve in the future
+
+With typed routes you get type validation when calling `router.push()` as well as autocompletion for the route path. It gives you:
+
+- Validation for [named routes](../essentials/named-routes.md) `name` and `params` properties
+- Autocompletion of the `to` prop when using the `<RouterLink>` component
+
+## Usage
+
+In order to benefit from typed routes, it is necessary to pass the `routes` option to the `as const`:
+
+```ts{6}
+const router = createRouter({
+  // ...
+  routes: [
+    { path: '/', name: 'home' },
+    { path: '/users/:id', name: 'user' },
+  ] as const, // <-- this is the important part
+})
+```
+
+This will give you a **typed router instance**. Go ahead and give it a try, start typing `router.push({ name: '|'}` and hit `ctrl` + `space` to autocomplete the route name. It will also autocomplete `params` if they exist and **give you a type error** if the name doesn't exist or if the provided params are missing any required params. Note that you can push a route **with no `params` property** and this will be considered valid for the types because `params` are always kept from the current route whenever possible.
+
+### Typed `router` instance
+
+It is possible to type `$router` and `useRouter()` to be the same type as the `router` instance we created above. To do this, we need to extend an interface. It's recommended to do so in the `router.ts` file, right after creating the router:
+
+```ts{5-9}
+export const router = createRouter({
+  // ...options
+})
+
+declare module 'vue-router' {
+  interface Config {
+    Router: typeof router
+  }
+}
+```
+
+### Typed `<RouterLink>`
+
+It's also possible to type the `to` prop of `<RouterLink>` by overriding the global type used by Vue. You can add this in the `router.ts` file, right after the previous snippet of code:
+
+```ts{1,9-13}
+import type { RouterLinkTyped } from 'vue-router'
+
+export const router = createRouter({
+  // ...options
+})
+
+// other code
+
+declare module 'vue' {
+  interface GlobalComponents {
+    RouterLink: RouterLinkTyped<typeof router>
+  }
+}
+```
+
+## Caveats
+
+Currently, typed routes are inferred at runtime with complex, costly types that become slow if you have a lot of routes. If you have more than 50 routes, you will should give this a try first to see how much it impacts the compilation time of your project.
+
+If you have [dynamic routes](../advanced/dynamic-routing.md), these cannot be typed and if you use [named routes](../essentials/named-routes.md), you won't be able to push to them so it's better not to use both at the same time.
+
+## Troubleshooting
+
+If you ever find something blocking you or making your types too slow, you can just remove the `as const` part to rollback to the previous version of the types. If something not mentioned here isn't working and you think it sohuld be working, please open an issue on [GitHub](https://github.com/vuejs/router/issues).