@capri-js/preact-router

preact-router

Connect your Preact components up to that address bar.

preact-router provides a <Router /> component that conditionally renders its children when the URL matches their path. It also automatically wires up <a /> elements to the router.

💁 Note: This is not a preact-compatible version of React Router. preact-router is a simple URL wiring and does no orchestration for you.

If you're looking for more complex solutions like nested routes and view composition, react-router works great with preact as long as you alias in preact/compat.

See a Real-world Example :arrow_right:

---

Usage Example

import Router from 'preact-router';
import { h, render } from 'preact';
/** @jsx h */

const Main = () => (
  <Router>
    <Home path="/" />
    <About path="/about" />
    // Advanced is an optional query
    <Search path="/search/:query/:advanced?" />
  </Router>
);

render(<Main />, document.body);

If there is an error rendering the destination route, a 404 will be displayed.

Handling URLS

:information_desk_person: Pages are just regular components that get mounted when you navigate to a certain URL. Any URL parameters get passed to the component as props.

Defining what component(s) to load for a given URL is easy and declarative. Querystring and :parameter values are passed to the matched component as props. Parameters can be made optional by adding a ?, or turned into a wildcard match by adding * (zero or more characters) or + (one or more characters):

<Router>
  <A path="/" />
  <B path="/b" id="42" />
  <C path="/c/:id" />
  <C path="/d/:optional?/:params?" />
  <D path="/e/:remaining_path*" />
  <E path="/f/:remaining_path+" />
  <F default />
</Router>

Lazy Loading

Lazy loading (code splitting) with preact-router can be implemented easily using the AsyncRoute module:

import AsyncRoute from 'preact-async-route';
<Router>
  <Home path="/" />
  <AsyncRoute
    path="/friends"
    getComponent={() => import('./friends').then(module => module.default)}
  />
  <AsyncRoute
    path="/friends/:id"
    getComponent={() => import('./friend').then(module => module.default)}
    loading={() => <div>loading...</div>}
  />
</Router>;

Active Matching & Links

preact-router includes an add-on module called match that lets you wire your components up to Router changes.

Here's a demo of <Match>, which invokes the function you pass it (as its only child) in response to any routing:

import Router from 'preact-router';
import Match from 'preact-router/match';

render(
  <div>
    <Match path="/">{({ matches, path, url }) => <pre>{url}</pre>}</Match>
    <Router>
      <div default>demo fallback route</div>
    </Router>
  </div>
);

// another example: render only if at a given URL:

render(
  <div>
    <Match path="/">{({ matches }) => matches && <h1>You are Home!</h1>}</Match>
    <Router />
  </div>
);

<Link> is just a normal link, but it automatically adds and removes an "active" classname to itself based on whether it matches the current URL.

import { Router } from 'preact-router';
import { Link } from 'preact-router/match';

render(
  <div>
    <nav>
      <Link activeClassName="active" href="/">
        Home
      </Link>
      <Link activeClassName="active" href="/foo">
        Foo
      </Link>
      <Link activeClassName="active" href="/bar">
        Bar
      </Link>
    </nav>
    <Router>
      <div default>this is a demo route that always matches</div>
    </Router>
  </div>
);

Default Link Behavior

Sometimes it's necessary to bypass preact-router's link handling and let the browser perform routing on its own.

This can be accomplished by adding a data-native boolean attribute to any link:

<a href="/foo" data-native>Foo</a>

Detecting Route Changes

The Router notifies you when a change event occurs for a route with the onChange callback:

import { render, Component } from 'preact';
import { Router, route } from 'preact-router';

class App extends Component {
  // some method that returns a promise
  isAuthenticated() {}

  handleRoute = async e => {
    switch (e.url) {
      case '/profile':
        const isAuthed = await this.isAuthenticated();
        if (!isAuthed) route('/', true);
        break;
    }
  };

  render() {
    return (
      <Router onChange={this.handleRoute}>
        <Home path="/" />
        <Profile path="/profile" />
      </Router>
    );
  }
}

Redirects

Can easily be implemented with a custom Redirect component;

import { Component } from 'preact';
import { route } from 'preact-router';

export default class Redirect extends Component {
  componentWillMount() {
    route(this.props.to, true);
  }

  render() {
    return null;
  }
}

Now to create a redirect within your application, you can add this Redirect component to your router;

<Router>
  <Bar path="/bar" />
  <Redirect path="/foo" to="/bar" />
</Router>

Custom History

It's possible to use alternative history bindings, like /#!/hash-history:

import { h } from 'preact';
import Router from 'preact-router';
import { createHashHistory } from 'history';

const Main = () => (
  <Router history={createHashHistory()}>
    <Home path="/" />
    <About path="/about" />
    <Search path="/search/:query" />
  </Router>
);

render(<Main />, document.body);

Programmatically Triggering Route

It's possible to programmatically trigger a route to a page (like window.location = '/page-2')

import { route } from 'preact-router';

route('/page-2'); // appends a history entry

route('/page-3', true); // replaces the current history entry

Nested Routers

The <Router> is a self-contained component that renders based on the page URL. When nested a Router inside of another Router, the inner Router does not share or observe the outer's URL or matches. Instead, inner routes must include the full path to be matched against the page's URL:

import { h, render } from 'preact';
import Router from 'preact-router';

function Profile(props) {
  // `props.rest` is the rest of the URL after "/profile/"
  return (
    <div>
      <h1>Profile</h1>
      <Router>
        <MyProfile path="/profile/me" />
        <UserProfile path="/profile/:user" />
      </Router>
    </div>
  );
}
const MyProfile = () => <h2>My Profile</h2>;
const UserProfile = props => <h2>{props.user}</h2>;

function App() {
  return (
    <div>
      <Router>
        <Home path="/" />
        <Profile path="/profile/:rest*" />
      </Router>
      <nav>
        <a href="/">Home</a>
        <a href="/profile/me">My Profile</a>
        <a href="/profile/alice">Alice's Profile</a>
      </nav>
    </div>
  );
}

render(<App />, document.body);

License

MIT