fix: solve prevUrl on first render issue (#7082)

Author: damianpumar

.changeset/dry-jobs-repair.md

@@ -0,0 +1,5 @@
+---
+'@builder.io/qwik-city': patch
+---
+
+FIX: the previous URL now is undefined on first render.

packages/docs/src/routes/docs/(qwikcity)/api/index.mdx

@@ -245,6 +245,9 @@ export const BackButton = component$(() => {
 
 The fallback in the nav function ensures that if the previous URL (loc.prevUrl) is not available, the user is redirected to a default path (eg. the root path /). This is useful in scenarios where the navigation history might not include a previous URL, such as when the user directly lands on a specific page without navigating from another page within the app.
 
+> Notice that the **loc.prevUrl** is only available when the user navigates to a page using the [`useNavigate()`](#usenavigate) or [`<Link>`](/docs/cookbook/nav-link). It is not available when the user navigates to a page using [`the anchor element`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a).
+
+
 ## `routeLoader$()`
 
 The `routeLoader$()` function is used to declare a new Server Loader in the given page/middleware or layout. Qwik City will execute all the declared loaders for the given route match. Qwik Components can later reference the loaders by importing them and calling the returned custom hook function in order to retrieve the data.

packages/qwik-city/src/runtime/src/qwik-city-component.tsx

@@ -375,7 +375,10 @@ export const QwikCityProvider = component$<QwikCityProps>((props) => {
         }
 
         // Update route location
-        routeLocation.prevUrl = prevUrl;
+        if (!isSamePath(trackUrl, prevUrl)) {
+          routeLocation.prevUrl = prevUrl;
+        }
+
         routeLocation.url = trackUrl;
         routeLocation.params = { ...params };