CODE EXAMPLE FOR JAVASCRIPT

react router v6

<HashRouter> 
    <Routes>
        <Route path='/app'> {/* put url base here and nest children routes */}
            <Route path='path1' element={ <Somecomponent1 /> } />
            <Route path='path2' element={ <Somecomponent2 /> } />
        </Route>
        <Route path="/*" element={<Navigate to="/app/path1" />}  /> {/* navigate to default route if no url matched */}
    </Routes>
</HashRouter>