buttermilk

• buttermilk
  • installation
  • usage
    • components
      • <Router>
      • <RoutingState>
      • <Link>
    • utilities
      • match(routes, url)
      • route()
    • holistic example
    • without a bundler
  • more examples
  • goals

installation

Grab the buttermilk package with your favorite package manager.

npm i buttermilk
yarn add buttermilk

usage

Setting up buttermilk involves placing a <Router> component on your page and feeding it an array of route definitions. If you learn better by reverse engineering, check out the holistic example.

A basic, starter setup:

import { Router } from 'buttermilk';
import React from 'react';

// whatever your folder structure looks like, etc.
import FooPage from '../foo';
import NotFoundPage from '../404';

class App extends React.Component {
  render() {
    return (
      <Router
        routes={[
          {
            path: '/foo',
            render: () => FooPage,
          }, {
            path: '*',
            render: () => NotFoundPage,
          }
        ]}
      />
    );
  }
}

Buttermilk has a highly flexible matching system, offering the following flavors of routing:

flavor	syntax
static	/foo
dynamic fragments	/foo/:id
optional fragments	/foo(/bar)
wildcard	/foo*
fallback	*
splat	/foo/**/bar.html
functional	yourValidationFunction(url)
regex	^(?=bar)/foo
query string	?foo=bar

The only hard rule is there must be a fallback route at the end of the routing chain: path: '*'. Otherwise, you are free to compose routes as it makes sense for your app.

A route configuration should have this shape:

{
  path: String | RegExp | Function,
  redirect: String?,
  render: Function?,  // note that this is required if "redirect" is not passed
}

Return whatever you'd like from the render function. A few ideas:

• A React component class

  render: () => HelloWorldPage,

• Some JSX

  render: () => <div>Hi!</div>,

• A string

  render: () => 'Howdy!',

• A promise resolving to one of the above (great for async-loading pages)

  render: () => import('./HelloWorld').then(mdl => mdl.default),

If it's a component class, Buttermilk will inject the routing context as props.

components

<Router>

The gist of Buttermilk's router is that it acts like a controlled component when used server-side (driven by props.url) and an uncontrolled one client-side (driven by the value of window.location.href and intercepted navigation events.)

In the browser, use either a <Link> component or the route() utility method to change routes. The router will also automatically pick up popstate events caused by user-driven browser navigation (forward, back buttons, etc.)

Available props:

/**
 * Provide a spinner or something to look at while the promise
 * is in flight if using async routes.
 */
loadingComponent: PropTypes.oneOfType([
  PropTypes.func,
  PropTypes.string,
]),

/**
 * An optional app runtime component. Think of it like the "shell" of your
 * app, so perhaps the outer container, nav bar, etc. You'll probably want to
 * put any "Provider" type components here that are intended to wrap your
 * whole application.
 */
outerComponent: PropTypes.oneOfType([
  PropTypes.func,
  PropTypes.string,
]),

routes: PropTypes.arrayOf(
  PropTypes.shape({

    /**
     * A RegExp, string, or function accepting the URL as
     * an argument and returning a boolean if valid.
     */
    path: PropTypes.oneOfType([
      PropTypes.instanceOf(RegExp),
      PropTypes.string,
      PropTypes.func,
    ]).isRequired,

    /**
     * A string URL path to a different route. If this is given,
     * then "render" is not required.
     */
    redirect: PropTypes.string,

    /**
     * A function that returns one of the following:
     *
     * 1. JSX.
     * 2. A React component class.
     * 3. A promise resolving to JSX or a React component class.
     */
    render: PropTypes.func,
  }),
).isRequired,

/**
 * A hook for reacting to an impending route transition. Accepts a promise
 * and will pause the route transition until the promise is resolved. Return
 * false or reject a given promise to abort the routing update.
 *
 * Provides currentRouting and nextRouting as arguments.
 */
routeWillChange: PropTypes.func,

/**
 * A hook for reacting to a completed route transition. It might be used
 * for synchronizing some global state if desired.
 *
 * Provides currentRouting and previousRouting as arguments.
 */
routeDidChange: PropTypes.func,

/**
 * A hook for synchronizing initial routing state.
 *
 * Providers initialRouting as an argument.
 */
routerDidInitialize: PropTypes.func,

/**
 * The initial URL to be used for processing, falls back to
 * window.location.href for non-SSR. Required for environments without
 * browser navigation eventing.
 */
url: PropTypes.string

<RoutingState>

A render prop higher order component (HOC) for arbitrarily-consuming routing state.

<RoutingState>
  {routingProps => {
    // routingProps.location  (the parsed current URL in window.location.* form)
    // routingProps.params    (any extracted dynamic params from the URL)
    // routingProps.route     (the current route)

    return /* some JSX */;
  }}
</RoutingState>

<Link>

A polymorphic anchor link component. On click/tap/enter if the destination matches a value route, the routing context will be modified without reloading the page. Otherwise, it will act like a normal anchor link.

If something other than an anchor tag is specified via props.as, a [role="link"] attribute will be added for basic assistive technology support.

Adds [data-active] if the given href matches the active route.

<Link as="button" href="/somewhere" target="_blank">
  Somewhere over the rainbow…
</Link>

Available props:

/**
 * An HTML tag name or valid ReactComponent class to be rendered. Must
 * be compatible with React.createElement.
 *
 * Defaults to an anchor "a" tag.
 */
as: PropTypes.oneOfType([
  PropTypes.func,
  PropTypes.string,
]),

/**
 * A valid relative or absolute URL string.
 */
href: PropTypes.string.isRequired,

/**
 * Any valid value of the anchor tag "target" attribute.
 *
 * See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attr-target
 *
 * Defaults to "_self".
 */
target: PropTypes.string,

utilities

match(routes, url)

This is an advanced API meant primarily for highly-custom server side rendering use cases. Provide your array of route defintions and the fully-resolved URL to receive the matched route, route context, and any suggested redirect.

import { match } from 'buttermilk';

const url = 'https://fizz.com/buzz';

const routes = [{
  path: '/foo',
  render: () => FooPage,
}, {
  path: '/bar',
  render: () => BarPage,
}, {
  path: '*',
  render: () => NotFoundPage,
}];

const { location, params, redirect, route } = match(routes, url);

When using this API, you'll probably want to have a more streamlined <Router> setup for the server since we're doing all the work upfront to find the correct route:

import { match, Router } from 'buttermilk';
import React from 'react';
import ReactDOMServer from 'react-dom/server';

import routes from '../routes';

/**
 * An example express middleware.
 */
export default function renderingMiddleware(req, res, next) {
  const url = req.protocol + '//' + req.get('host') + req.originalUrl;

  const { location, params, redirect, route } = match(routes, url);

  if (redirect) return res.redirect(redirect);

  const html = ReactDOMServer.renderToString(
    <Router
      url={url}
      routes={[{
        ...route,
        path: '*',
      }]}
    />
  );

  /**
   * route.title below is an example arbitrary prop you could add to the
   * route definition if desired
   */
  res.send(`
    <!doctype html>
    <html>
      <head><title>${route.title}</title></head>
      <body>${html}</body>
    </html>
  `);
}

route()

Use this API to programmatically change the route browser-side. It uses pushState or replaceState under the hood, depending on if you pass the second argument. Defaults to creating a new browser history entry.

// signature: route(url: String, addNewHistoryEntry: Boolean = true)

route('/some/other/url');

holistic example

See it live: https://codesandbox.io/s/20q311nn6n

/* Home.js */
export default () => "Home";

/* index.js */
import React from "react";
import ReactDOM from "react-dom";

import { Router, RoutingState, Link } from "buttermilk";

const App = props => (
  <div>
    <header>
      <h1>My sweet website</h1>
    </header>

    <nav>
      <Link href="/">Home</Link>
      <Link href="/blep/kitter">Kitter Blep!</Link>
      <Link href="/blep/corg">Corg Blep!</Link>
    </nav>

    <main>{props.children}</main>
  </div>
);

const NotFound = () => (
  <div>
    <h2>Oh noes, a 404 page!</h2>
    <RoutingState>
      {routing => (
        <p>
          No page was found with the path:
          <code>{routing.location.pathname}</code>
        </p>
      )}
    </RoutingState>

    <p>
      <Link href="/">Let's go back home.</Link>
    </p>
  </div>
);

const routes = [
  {
    path: "/",
    render: () => import("./Home").then(mdl => mdl.default),
  },
  {
    path: "/blep/:animal",
    render: routing => (
      <img
        alt="Bleppin'"
        src={
          routing.params.animal === "corg"
            ? "http://static.damnlol.com/media/bc42fc943ada24176298871de477e0c6.jpg"
            : "https://i.imgur.com/OvbGwwI.jpg"
        }
      />
    ),
  },
  {
    path: "*",
    render: () => NotFound,
  },
];

const root = document.body.appendChild(document.createElement("div"));

ReactDOM.render(<Router routes={routes} outerComponent={App} />, root);

without a bundler

You can also use consume Buttermilk from a CDN like unpkg:

https://unpkg.com/buttermilk@1.1.0/dist/umd.js
https://unpkg.com/buttermilk@1.1.0/dist/umd.min.js

The exports will be accessible at window.Buttermilk. Note that this requires react >= 16.3 (window.React) and prop-types (window.PropTypes) to also be accessible in the window scope.

more examples

• holistic example + animated route transitions: https://codesandbox.io/s/30llnkwj5q

goals

• centrally-managed routing
• fast
• first-class async support
• HMR-friendly
• obvious API
• small
• SSR