page router logo

Tiny ~1200 byte Express-inspired client-side router.

page('/', index)
page('/user/:user', show)
page('/user/:user/edit', edit)
page('/user/:user/album', album)
page('/user/:user/album/sort', sort)
page('*', notfound)
page()

Running examples

To run examples do the following to install dev dependencies an run the example server:

$ npm install
$ node examples
$ open http://localhost:3000

Currently we have examples for:

API

page(path, callback[, callback ...])

Defines a route mapping path to the given callback(s).

page('/', user.list)
page('/user/:id', user.load, user.show)
page('/user/:id/edit', user.load, user.edit)
page('*', notfound)

Links that are not of the same origin are disregarded
and will not be dispatched.

page(callback)

This is equivalent to page('*', callback) for generic "middleware".

page(path)

Navigate to the given path.

$('.view').click(function(e){
  page('/user/12')
  e.preventDefault()
})

page.show(path)

Identical to page(path) above.

page([options])

Register page's popstate / click bindings. If you're
doing selective binding you'll like want to pass { click: false }
to specify this yourself. The following options are available:

page.start([options])

Identical to page([options]) above.

page.stop()

Unbind both the popstate and click handlers.

page.base([path])

Get or set the base path. For example if page.js
is operating within "/blog/*" set the base path to "/blog".

Context#save()

Saves the context using replaceState(). For example
this is useful for caching HTML or other resources
that were loaded for when a user presses "back".

Routes are passed Context objects, these may
be used to share state, for example ctx.user =,
as well as the history "state" ctx.state that
the pushState API provides.

Context#canonicalPath

Pathname including the "base" (if any) and query string "/admin/login?foo=bar".

Context#path

Pathname and query string "/login?foo=bar".

Context#querystring

Query string void of leading ? such as "foo=bar", defaults to "".

Context#pathname

The pathname void of query string "/login".

Context#state

The pushState state object.

Context#title

The pushState title.

Routing

The router uses the same string-to-regexp conversion
that Express does, so things like ":id", ":id?", and "*" work
as you might expect.

Another aspect that is much like Express is the ability to
pass multiple callbacks. You can use this to your advantage
to flatten nested callbacks, or simply to abstract components.

Separating concerns

For example suppose you had a route to edit users, and a
route to view users. In both cases you need to load the user.
One way to achieve this is with several callbacks as shown here:

page('/user/:user', load, show)
page('/user/:user/edit', load, edit)

Using the * character we could alter this to match all
routes prefixed with "/user" to achieve the same result:

page('/user/*', load)
page('/user/:user', show)
page('/user/:user/edit', edit)

Likewise * may be used as catch-alls after all routes
acting as a 404 handler, before all routes, in-between and
so on. For example:

page('/user/:user', load, show)
page('*', function(){
  $('body').text('Not found!')
})

Default 404 behaviour

By default when a route is not matched,
page.js will invoke page.stop() to unbind
itself, and proceed with redirecting to the
location requested. This means you may use
page.js with a multi-page application without
explicitly binding to certain links.

Working with parameters and contexts

Much like request and response objects are
passed around in Express, page.js has a single
"Context" object. Using the previous examples
of load and show for a user, we can assign
arbitrary properties to ctx to maintain state
between callbacks.

First to build a load function that will load
the user for subsequent routes you'll need to
access the ":id" passed. You can do this with
ctx.params.NAME much like Express:

function load(ctx, next){
  var id = ctx.params.id
}

Then perform some kind of action against the server,
assigning the user to ctx.user for other routes to
utilize. next() is then invoked to pass control to
the following matching route in sequence, if any.

function load(ctx, next){
  var id = ctx.params.id
  $.getJSON('/user/' + id + '.json', function(user){
    ctx.user = user
    next()
  })
}

The "show" function might look something like this,
however you may render templates or do anything you
want. Note that here next() is not invoked, because
this is considered the "end point", and no routes
will be matched until another link is clicked or
page(path) is called.

function show(ctx){
  $('body')
    .empty()
    .append('

' + ctx.user.name + '

'); }

Finally using them like so:

page('/user/:id', load, show)

Working with state

When working with the pushState API,
and thus page.js you may optionally provide
state objects available when the user navigates
the history.

For example if you had a photo application
and you performed a relatively expensive
search to populate a list of images,
normally when a user clicks "back" in
the browser the route would be invoked
and the query would be made yet-again.

Perhaps the route callback looks like this:

function show(ctx){
  $.getJSON('/photos', function(images){
    displayImages(images)
  })
}

You may utilize the history's state
object to cache this result, or any
other values you wish. This makes it
possible to completely omit the query
when a user presses back, providing
a much nicer experience.

function show(ctx){
  if (ctx.state.images) {
    displayImages(ctx.state.images)
  } else {
    $.getJSON('/photos', function(images){
      ctx.state.images = images
      ctx.save()
      displayImages(images)
    })
  }
}

NOTE: ctx.save() must be used
if the state changes after the first
tick (xhr, setTimeout, etc), otherwise
it is optional and the state will be
saved after dispatching.

Matching paths

Here are some examples of what's possible
with the string to RegExp conversion.

Match an explicit path:

page('/about', callback)

Match with required parameter accessed via ctx.params.name:

page('/user/:name', callback)

Match with several params, for example /user/tj/edit or
/user/tj/view.

page('/user/:name/:operation', callback)

Match with one optional and one required, now /user/tj
will match the same route as /user/tj/show etc:

page('/user/:name/:operation?', callback)

Use the wildcard char "" to match across segments,
available via ctx.params[N] where N is the
index of "
" since you may use several. For example
the following will match /user/12/edit, /user/12/albums/2/admin
and so on.

page('/user/*', loadUser)

Named wildcard accessed, for example /file/javascripts/jquery.js
would provide "/javascripts/jquery.js" as ctx.params.file:

page('/file/:file(*)', loadUser)

And of course RegExp literals, where the capture
groups are available via ctx.params[N] where N
is the index of the capture group.

page(/^\/commits\/(\d+)\.\.(\d+)/, loadUser)

Plugins

Currently there are no official plugins,
however examples/query-string/query.js
will provide a parsed ctx.query object
derived from https://github.com/visionmedia/node-querystring.

Usage by using "*" to match any path
in order to parse the query-string:

page('*', parse)
page('/', show)
page()

function parse(ctx, next) {
  ctx.query = qs.parse(location.search.slice(1));
  next();
}

function show(ctx) {
  if (Object.keys(ctx.query).length) {
    document
      .querySelector('pre')
      .textContent = JSON.stringify(ctx.query, null, 2);
  }
}

Running tests

$ npm install
$ make test
$ open http://localhost:3000/

License

(The MIT License)

Copyright (c) 2012 TJ Holowaychuk <tj@vision-media.ca>

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.