Fix docs on NavLink w.r.t. links to the root route and the end prop (#10757)

* Fix docs on NavLink w.r.t. links to the root route and the end prop

* Update

Author: brophdawg11

docs/components/nav-link.md

@@ -84,29 +84,17 @@ You can pass a render prop as children to customize the content of the `<NavLink
 
 The `end` prop changes the matching logic for the `active` and `pending` states to only match to the "end" of the NavLink's `to` path. If the URL is longer than `to`, it will no longer be considered active.
 
-Without the end prop, this link is always active because every URL matches `/`.
-
-```tsx
-<NavLink to="/">Home</NavLink>
-```
-
-To match the URL "to the end" of `to`, use `end`:
-
-```tsx
-<NavLink to="/" end>
-  Home
-</NavLink>
-```
-
-Now this link will only be active at `"/"`. This works for paths with more segments as well:
-
 | Link                          | URL          | isActive |
 | ----------------------------- | ------------ | -------- |
 | `<NavLink to="/tasks" />`     | `/tasks`     | true     |
 | `<NavLink to="/tasks" />`     | `/tasks/123` | true     |
 | `<NavLink to="/tasks" end />` | `/tasks`     | true     |
 | `<NavLink to="/tasks" end />` | `/tasks/123` | false    |
 
+**A note on links to the root route**
+
+`<NavLink to="/">` is an exceptional case because _every_ URL matches `/`. To avoid this matching every single route by default, it effectively ignores the `end` prop and only matches when you're at the root route.
+
 ## `caseSensitive`
 
 Adding the `caseSensitive` prop changes the matching logic to make it case sensitive.

packages/react-router-dom/__tests__/nav-link-active-test.tsx

@@ -317,6 +317,42 @@ describe("NavLink", () => {
       expect(anchors.map((a) => a.props.className)).toEqual(["active", ""]);
     });
 
+    it("matches the root route with or without the end prop", () => {
+      let renderer: TestRenderer.ReactTestRenderer;
+      TestRenderer.act(() => {
+        renderer = TestRenderer.create(
+          <MemoryRouter>
+            <Routes>
+              <Route index element={<NavLink to="/">Root</NavLink>} />
+            </Routes>
+          </MemoryRouter>
+        );
+      });
+
+      let anchor = renderer.root.findByType("a");
+      expect(anchor.props.className).toMatch("active");
+
+      TestRenderer.act(() => {
+        renderer = TestRenderer.create(
+          <MemoryRouter>
+            <Routes>
+              <Route
+                index
+                element={
+                  <NavLink to="/" end>
+                    Root
+                  </NavLink>
+                }
+              />
+            </Routes>
+          </MemoryRouter>
+        );
+      });
+
+      anchor = renderer.root.findByType("a");
+      expect(anchor.props.className).toMatch("active");
+    });
+
     it("does not automatically apply to root non-layout segments", () => {
       let renderer: TestRenderer.ReactTestRenderer;
       TestRenderer.act(() => {