Oaf React Router

An accessible wrapper for React Router.

Compatibility

| React Router | history | Oaf React Router | |--------------|--------------------------------------------------|------------------| | 6.4+ | NA | 4.0.0 | | 6.4+ with redux-first-history | 5 | 3.0.1 | | 6.0 - 6.3 | 5 | 3.0.1 | | 5 | 4 | 2.1.1 |

DOM-only (no React Native support).

Features

• Reset scroll and focus after PUSH and REPLACE navigation
• Restore scroll and focus after POP navigation
• Set the page title after navigation
• Announce navigation to users of screen readers
• Hash fragment support

Reset scroll and focus after PUSH and REPLACE navigation

React Router does not reset the window's scroll position or the focused element after page navigation.

The React Router documentation sketches a "scroll to top" approach that scrolls the window back to the top of the page after navigation, emulating native browser behavior. There are also packages to do this for you, such as trevorr/react-scroll-manager or react-router-scroll-top. Unfortunately, these approaches address only the scroll half of the question, ignoring keyboard focus:

One of the unique features of single page applications that can create challenges for people using screen readers is that there’s never a page refresh, only view refreshes. As a result, the focused element often disappears from the interface, and the person using the screen reader is left searching for clues as to what happened and what’s now showing in the application view. Places where focus is commonly lost include: page changes, item deleting, modal closing, and expanding and closing record details.

Oaf React Router fixes this by moving focus to something it calls the "primary focus target" after navigation, which by default is the first h1 element inside the page's main element, but this is configurable. For advice on what this focus target should be, see Marcy Sutton's recommendations.

In addition to moving focus, Oaf React Router will also scroll the primary focus target into view, so you don't need to worry about scrolling to the top of the page after a page navigation.

In a non-single page app website, a web browser will reset focus to the very top of the document after navigation (at the same time that it scrolls to top). You can emulate this with Oaf React Router by setting the primary focus target to body instead of the default main h1.

See:

• https://reacttraining.com/react-router/web/guides/scroll-restoration
• https://github.com/ReactTraining/react-router/issues/5210
• https://medium.com/@robdel12/single-page-apps-routers-are-broken-255daa310cf
• https://www.gatsbyjs.org/blog/2019-07-11-user-testing-accessible-client-routing

Restore scroll and focus after POP navigation

After a POP navigation (i.e. after navigation back or forward through history) browsers typically restore focus and scroll position to where they were when the user last navigated away from that page.

React Router does not emulate this, so Oaf React Router takes care of it for you. Note that browsers such as Firefox and Safari will restore both scroll position and the last focused element, but for some reason Chrome restores only the scroll position, not the focused element. To imitate this, Oaf React Router will move focus to the primary focus target (as described in the previous section) instead of to the last focused element when a POP navigation occurs in Chrome.

Note that there is a proposed scroll restoration standard but it is not widely implemented and it only addresses scroll position, not focus (notice a theme emerging?) so it is of no use to us.

See:

• https://github.com/ReactTraining/react-router/issues/3950
• https://developer.mozilla.org/de/docs/Web/API/History#Browser_compatibility
• https://github.com/Fyrd/caniuse/issues/1889

Set the page title after navigation

Every page in your React app must have a unique and descriptive title. Oaf React Router will set the page title for you using a function that maps from locations to page titles. You must supply this function. For how to provide this function, see the usage section below.

See:

• https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-title.html

Announce navigation to users of screen readers

Oaf React Router will announce page navigation events to screen reader users via a visually hidden aria-live element. Announcing navigation is required because:

By default, Oaf React Router will announce "navigated to foo" where "foo" is the page title returned by the function described in the previous section. You can override this to support localization, etc.

See:

• https://almerosteyn.com/2017/03/accessible-react-navigation

Hash fragment support

Another native browser feature that React Router doesn't emulate is scrolling to the element identified by the hash fragment in a URL. For example, if you load https://en.wikipedia.org/wiki/Firefox#Performance, your browser will scroll down to the <span id="Performance"> automatically.

There are other libraries that tackle this issue—for example rafrex/react-router-hash-link—but they typically only address scroll to the exclusion of focus (there's that theme again).

Oaf React Router implements this for you, taking care of both focus and scroll.

A caveat here is that the identified element must exist in the DOM straight after the route is rendered. If the element won't exist for some time, e.g. until after an API response, then Oaf React Router won't focus or scroll to it, falling back on the primary focus target.

Installation

# yarn
yarn add oaf-react-router

# npm
npm install oaf-react-router

Basic Usage

React Router 5

- import { BrowserRouter as Router } from "react-router-dom";
+ import { Router } from "react-router-dom";
+ import { createBrowserHistory } from "history";
+ import { wrapHistory } from "oaf-react-router";

+ const history = createBrowserHistory(); // or createHashHistory()
+ wrapHistory(history);

ReactDOM.render((
-  <Router>
+  <Router history={history}>
    ...
  </Router>
), document.getElementById("root"));

React Router 6.0 to 6.3

- import { BrowserRouter } from "react-router-dom";
+ import { unstable_HistoryRouter as HistoryRouter } from "react-router-dom";
+ import { createBrowserHistory } from "history";
+ import { wrapHistory } from "oaf-react-router";

+ const history = createBrowserHistory(); // or createHashHistory()
+ wrapHistory(history);

ReactDOM.render((
-  <BrowserRouter>
+  <HistoryRouter history={history}>
    ...
-  <BrowserRouter>
+  </HistoryRouter>
), document.getElementById("root"));

React Router 6.4+ with redux-first-history

Stick to version 3.x.y of oaf-react-router.

React Router 6.0 to 6.3 used history but 6.4 dropped it. Even with React Router 6.4, redux-first-history continues to use the history package. For this reason, redux-first-history provides its own HistoryRouter. See https://github.com/salvoravida/redux-first-history#usage. For these reasons, if you're using React Router 6.4+ with redux-first-history you can continue to use version 3.x.y of oaf-react-router (the last version to support history). You just need to use redux-first-history's HistoryRouter, which boils down to doing the above, but replacing the line

+ import { unstable_HistoryRouter as HistoryRouter } from "react-router-dom";

with the line

+ import { HistoryRouter } from "redux-first-history/rr6";

See https://github.com/salvoravida/redux-first-history/issues/95

React Router 6.4+

Use version 4.0.0 or later of oaf-react-router.

As per https://github.com/remix-run/react-router/issues/9422#issuecomment-1302564759, with the addition of a call to wrapRouter.

import { createBrowserRouter, RouterProvider } from "react-router-dom";
+ import { wrapRouter } from "oaf-react-router";

const router = createBrowserRouter([
  // match everything with "*"
  { path: "*", element: <App /> }
])

+ wrapRouter(router);

ReactDOM.createRoot(document.getElementById('root')).render(
  <React.StrictMode>
    <RouterProvider router={router} />
  </React.StrictMode>
)

Advanced Usage

const history = createBrowserHistory();

const settings = {
  announcementsDivId: "announcements",
  primaryFocusTarget: "main h1, [role=main] h1",
  // This assumes you're setting the document title via some other means (e.g. React Helmet).
  // If you're not, you should return a unique and descriptive page title for each page
  // from this function and set `setPageTitle` to true.
  documentTitle: (location: Location) => document.title,
  // BYO localization
  navigationMessage: (title: string, location: Location, action: Action): string => `Navigated to ${title}.`,
  // Return false if you're handling focus yourself for a specific history action.
  shouldHandleAction: (previousLocation: Location, nextLocation: Location, action: Action) => true,
  disableAutoScrollRestoration: true,
  announcePageNavigation: true,
  setPageTitle: false,
  handleHashFragment: true,
  // Set this to false if you are using HashRouter or MemoryRouter.
  restorePageStateOnPop: true,
  // Set this to true for smooth scrolling.
  // For browser compatibility you might want iamdustan's smoothscroll polyfill https://github.com/iamdustan/smoothscroll
  smoothScroll: false,
};

wrapHistory(history, settings);

// Or wrapRouter(router, settings)

A note on setting document title

You may already be using React Helmet or some other technique to set the document title on route change. That's fine, just be mindful of how you might announce page navigation to users of screen readers and other assistive technology.

In the case of React Helmet, you might do something like this:

1. Set both setPageTitle and announcePageNavigation to false in the config object you pass to Oaf React Router's wrapHistory function.
2. Add a handler function to React Helmet's onChangeClientState callback.
3. Announce page navigation using something like the announce function from Oaf Side Effects (which is what Oaf React Router itself uses).

A note on focus outlines

You may see focus outlines around your h1 elements (or elsewhere, per primaryFocusTarget) when using Oaf React Router.

You might be tempted to remove these focus outlines with something like the following:

[tabindex="-1"]:focus {
  outline: 0 !important;
}

Don't do this! Focus outlines are important for accessibility. See for example:

• https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-focus-visible.html
• https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/F78
• http://www.outlinenone.com/
• https://github.com/twbs/bootstrap/issues/28425
• Although there is some debate: https://github.com/w3c/wcag/issues/1001

All that said, if you absolutely must remove focus outlines (stubborn client, stubborn boss, stubborn designer, whatever), consider using :focus-visible (and its polyfill) so focus outlines are only hidden from mouse users, not keyboard users.

Inspiration and prior art

• https://github.com/rafrex/react-router-hash-link
• https://github.com/trevorr/react-scroll-manager
• https://medium.com/@gajus/making-the-anchor-links-work-in-spa-applications-618ba2c6954a
• https://almerosteyn.com/2017/03/accessible-react-navigation
• https://reach.tech/router/accessibility
• https://medium.com/@robdel12/single-page-apps-routers-are-broken-255daa310cf

Related issues

• https://github.com/alphagov/govuk-frontend/issues/2412
• https://github.com/remix-run/react-router/issues/5210

See also

• Oaf Routing
• Oaf Side Effects
• @axe-core/react
• eslint-plugin-jsx-a11y
• React Accessibility