RouterRouter

A very small JavaScript routing library extracted from Backbone's Router.

Using a modified version of Backbone's routing code, RouterRouter provides Backbone-style route definition while remaining a small, standalone, dependency-free library. RouterRouter maps specified routes (the value returned from window.location.pathname) to user-defined actions. This approach may be useful for websites with predictable URLs and modular, component-specific JavaScript.

Key Features

• Inspired by Backbone's routing API
• Dependency-free
• JavaScript module (ESM), CommonJS, and browser global (window.RouterRouter) support

Getting RouterRouter

You've got a couple options for adding RouterRouter to your project:

• Download a release from GitHub and do it yourself (old school).
• Install using npm: npm install @jgarber/routerrouter --save
• Install using Yarn: yarn add @jgarber/routerrouter

Usage

Basic

A basic example, matching a route:

const router = new RouterRouter();

// matches https://example.com/posts
router.route("/posts", () => console.log("Hello!"));

Another example, this time using a named parameter to match a route:

const router = new RouterRouter();

// matches https://example.com/posts/hello-world and logs "hellow-world"
router.route("/posts/:slug", (slug) => console.log(slug));

RouterRouter supports a number of different matchers which are outlined below in the Pattern Matching section.

Advanced

A more complex example, demonstrating an alternative method of defining routes and actions:

const router = new RouterRouter({
  // Routes are defined in the `routes` object:
  routes: {
    // Actions may be defined inline:
    "/": () => {
      console.log("This route matches the root URL");
    },

    // Routes may also be mapped to named actions:
    "/posts": "postsPageAction",

    // Matched patterns in routes are passed to actions
    // in the order they appear in the route:
    "/posts/:year/:month/:slug", "postPageAction"
  },

  postPageAction: (year, month, slug) => {
    // Logs strings like "2018", "06", "hello-world"
    console.log(year, month, slug);
  },

  postsPageAction: () => {
    console.log("This route matches the /posts URL");
  }
});

Pattern Matching

RouterRouter will match URL patterns similar to Backbone's Router with the notable exception that routes must begin with a slash (/).

Pro Tip: It's possible to define multiple routes and actions that match similar URLs (e.g. /posts and /:section). This could lead to confusion, though, so be judicious when defining routes and actions.

String Matching

Route	Matched URLs
/	https://example.com
/posts	https://example.com/posts
/posts/hello-world	https://example.com/posts/hello-world

Named Parameters

Named parameters match patterns in routes and pass the captured values to the associated action for reuse. Captured values are passed to the action in the order they appear in the route. Named parameters are limited to strings of characters appearing between slashes (/) in a URL.

Route	Matched URLs	Matched Patterns
/posts/:slug	https://example.com/posts/hello-world	hello-world
/:section/:subsection	https://example.com/solar-systems/milky-way	solar-systems, milky-way

Wildcard Parameters

Wildcard parameters match patterns in routes including slashes (/) in URLs. For clarity, wildcard parameters may optionally include a named identifier (e.g. *wildcard_parameter). Similar to named parameters, captured values are passed to the action in the order they appear in the route and may include slashes.

Route	Matched URLs	Matched Patterns
/posts/*/06/*	https://example.com/posts/2018/06/23	2018, 23
/posts/*years_months/23	https://example.com/posts/2018/06/23	2018/06

Optional Parameters

Optional parameters match patterns in routes conditionally and pass captured values to the specified action. By default, matched optional parameters are not captured. In cases where an optional parameter does not appear in the URL, null is passed to the action. Optional parameter matching is rather powerful and complex, so use this feature with care!

Route	Matched URLs	Matched Patterns
/posts(/)	https://example.com/posts
	https://example.com/posts/
/posts(/:slug)	https://example.com/posts
	https://example.com/posts/hello-world	hello-world
(/:section)/2018	https://example.com/2018
	https://example.com/posts/2018	posts
	https://example.com/archives/2018	archives

Regular Expressions

RouterRouter supports route definitions using regular expressions. Regular expression matching may be as simple or complex as necessary and non-passive captured groups will be passed to the mapped action in the order they appear in the regular expression.

Pro Tip: Routes defined using regular expressions are not limited to matching the entire value of window.location.pathname and therefore do not need to begin with a slash (/). This feature can be used to interesting effect.

const router = new RouterRouter();

router.route(/\/comments\/?$/, () => {
  console.log("This route matches URLs ending in /comments or /comments/");
});

// Logs "links", "photos", or "posts"
router.route(/^\/(links|photos|posts)\/(?:.*)$/, (section) => console.log(section));

Examples

For a full-featured RouterRouter demonstration, check out the demo page and the example files.

Browser Support

RouterRouter works in modern browsers. The library makes use of several new(ish) JavaScript features and, in an effort to remain as lightweight and dependency-free as possible, leaves it up to you to choose whether or not to polyfill features for older browsers.

Limitations

RouterRouter matches the portion of a URL returned by window.location.pathname. This does not include other aspects of the Location interface like query parameters (e.g. ?search=why+does+the+sun+shine). Within an action, the Location interface may be used directly (window.location) or indirectly:

const router = new RouterRouter();

// Logs the internally cached version of `window.location`
console.log(router.location);

RouterRouter doesn't natively support the HTML5 History API. It may be possible to use RouterRouter with this feature, but for now, keeping the library as small as possible remains the project's primary goal.

Acknowledgments

Credit for the really difficult parts of RouterRouter goes to Jeremy Ashkenas, DocumentCloud, Investigative Reporters & Editors, and everyone else who has contributed code to Backbone.

RouterRouter is written and maintained by Jason Garber and is another in a growing collection of small, curiously-named JavaScript utilities:

• CashCash, a very small DOM library inspired by jQuery.
• RadioRadio, a very small PubSub library.
• TemplateTemplate, a very small <template> manipulation library.

License

Like Backbone, RouterRouter is freely available under the MIT License. Use it, learn from it, fork it, improve it, change it, tailor it to your needs.