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Sparou - Single Page Application Router

Sparou provides "just enough structure" to navigate a single page web application.


Sparou includes a simple router. It supports URL templates with named parts, and allows you to order routes by precedence. A route is associated with a page name, and is used to resolve which page is being requested.

The router is bi-directional. It can resolve page name and parameters from URLs, and it can generate URLs from a page name and parameters. The router also parses and exposes query string parameters, but cannot route based on them.


A page is an object with some hooks on it. When a page is requested, Sparou will perform the following steps:

  • Try to call canUnload on the currently loaded page. If this function returns false, nothing more happens. If there is no current page, the current page does not implement canUnload, or the current page's canUnload returns anything other than false, Sparou continues with unloading the current page.
  • Call onUnload on the current page, if there is one (and it defines the onUnload hook). This allows for performing state cleanup before loading a new URL.
  • Call onLoad on the page matching the new URL. The routing resolution is passed as an argument.

API docs

const appNav = navigateApp({prefix})

Create an application navigator. The prefix is optional, and can be set if your application is not served from the host root (e.g. your app is at


Load the new URL.


Like loadURL, but also push the url to the browser.

nav.getURL(pageName, params)

Use the bi-directional router to generate a URL from the page name and parameters.


Returns the URL corresponding to the current page and current query parameters. You can modify the location query and have it reflected in the URL returned from getCurrentURL.

nav.updateQueryParams({id: 42});
nav.getCurrentURL(); // ...?id=42 


Add some URL query parameters. This will cause the app to refresh with the new query parameters included in the URL. The new URL will also be loaded in the browser.


Kick things off by loading location.href.


Pages are plain old JavaScript objects.


The user navigated to this page. location is described with the router below.


Return false to stop the user from navigating away from this page. Useful if there is unsaved changes etc. The user will probably appreciate it if you provide a visual clue that the navigation was prevented.


Called before leaving this page to load another. Can be used to clean up page-specific state etc.

The router

The router is not exposed directly, although it is completely possible to use it on its own if desired.

const routingTable = createRoutes(routes[, {prefix}])

Creates a routing table. routes is an array of routes, where each route is a tuple of [pageName, urlTemplate]. The prefix can be used to ignore static URL prefixes, e.g. to target a URL like /my/app/news/23 with the route /news/:id and the prefix /my/app.

const url = toURLString({path, query})

Produces a URL string from a path and a query parameter object.

const url = getURL(routes, page, params)

Generates the URL to the given page type with the given parameters.

const location = getLocation(routes, url)

Returns the matching page from the routing table for the giving URL. If no route matches, it returns null. The location description includes the following properties:

String page

The name of the matching page.

String url

The URL matched against.

String path

Only the path part of the URL matched against.

Object params

Parameters matched from the route. Any :paramName placeholder from URL templates are included. For instance, if the matching route was /stuff/:id, then params will contain the id property.

Object query

The query string, parsed into an object.