WARNING: This documentation is for an old version of mithril! Please see the current docs for more accurate info.


Routing is a system that allows creating Single-Page-Applications (SPA), i.e. applications that can go from a page to another without causing a full browser refresh.

It enables seamless navigability while preserving the ability to bookmark each page individually, and the ability to navigate the application via the browser's history mechanism.

This method overloads four different units of functionality:

  • m.route(rootElement, defaultRoute, routes) - defines the available URLs in an application, and their respective components

  • m.route(path) - redirects to another route

  • m.route() - returns the currently active route

  • m.route(element) - an extension to link elements that unobtrusively abstracts away the routing mode

Routing is single-page-application (SPA) friendly, and can be implemented using either location.hash, HTML5 URL rewriting or location.querystring. See m.route.mode for the caveats of each implementation.

Defining routes


To define a list of routes, you need to specify a host DOM element, a default route and a key-value map of possible routes and respective components to be rendered. You don't need to call m.mount to initialize your components if you define a list of routes - m.route calls it for you.

The example below defines three routes, to be rendered in <body>. Home, Login and Dashboard are components. We'll see how to define a component in a bit.

m.route(document.body, "/", {
    "/": Home,
    "/login": Login,
    "/dashboard": Dashboard,

Routes can take arguments, by prefixing words with a colon :

The example below shows a route that takes an userID parameter

//a sample component
var Dashboard = {
    controller: function() {
        return {id: m.route.param("userID")}
    view: function(controller) {
        return m("div", controller.id);

//setup routes to start w/ the `#` symbol
m.route.mode = "hash";

//define a route
m.route(document.body, "/dashboard/johndoe", {
    "/dashboard/:userID": Dashboard

This redirects to the URL http://server/#/dashboard/johndoe and yields:


Above, dashboard is a component. It contains a controller and a view properties. When the URL matches a route, the respective component's controller is instantiated and passed as a parameter to the view.

In this case, since there's only one route, the app redirects to the default route "/dashboard/johndoe".

The string johndoe is bound to the :userID parameter, which can be retrieved programmatically in the controller via m.route.param("userID").

The m.route.mode defines which part of the URL to use for routing.

Variadic routes

We can append an ellipsis (...) to the name of a route argument to allow it to match URL snippets that contain slashes:

m.route(document.body, "/files/pictures/pic1.jpg", {
    "/files/:file...": gallery

m.route.param("file") === "pictures/pic1.jpg"
m.route(document.body, "/blog/2014/01/20/articles", {
    "/blog/:date.../articles": articleList

m.route.param("date") === "2014/01/20"

Note that Mithril checks for route matches in the order the routes are defined, so you should put variadic routes at the bottom of the list to prevent them from matching other more specific routes.

m.route(document.body, "/blog/archive/2014", {
    "/blog/:date...": Component1, //for the default path in the line above, this route matches first!
    "/blog/archive/:year": Component2

m.route.param("date") === "archive/2014"

//the routes should be flipped around to get `m.route.param("year") == "2014"`

Routes with querystrings

In addition to route parameters, it's possible to pass arbitrary data to m.route.param using the querystring


var sortBy = m.route.param("sortby") // "date"
var dir = m.route.param("dir") // "desc"

Running clean up code on route change

If a component's controller implements an instance method called onunload, this method will be called when a route changes.

var Home = {
    controller: function() {
        return {
            onunload: function() {
                console.log("unloading home component");
    view: function() {
        return m("div", "Home")

var Dashboard = {
    controller: function() {},
    view: function() {}

//go to the default route (home)
m.route(document.body, "/", {
    "/": Home,
    "/dashboard": Dashboard,

//re-route to dashboard
m.route("/dashboard"); // logs "unloading home component"

This mechanism is useful to clear timers and unsubscribe event handlers. If you have a hierarchy of components, you can recursively call onunload on all the components in the tree or use a pubsub library to unload specific components on demand.


How to read signatures

void route(DOMElement rootElement, String defaultRoute, Object<Component> routes) { String mode, String param(String key), String buildQueryString(Object data), Object parseQueryString(String data) }

    Component :: Object { void controller(), void view(Object controllerInstance) }
  • DOMElement root

    A DOM element which will contain the view's template.

  • String defaultRoute

    The route to redirect to if the current URL does not match any of the defined routes

  • Object routes

    A key-value map of possible routes and their respective components. Keys are expected to be absolute pathnames, but can include dynamic parameters. Dynamic parameters are words preceded by a colon :

    {'/path/to/page/': pageComponent} - a route with a basic pathname

    {'/path/to/page/:id': pageComponent} - a route with a pathname that contains a dynamic parameter called id. This route would be selected if the URL was /path/to/page/1, /path/to/page/test, etc

    {'/user/:userId/book/:bookId': userBookComponent} - a route with a pathname that contains two parameters

    Dynamic parameters are wild cards that allow selecting a component based on a URL pattern. The values that replace the dynamic parameters in a URL are available via m.route.param()

    Note that the URL component used to resolve routes is dependent on m.route.mode. By default, the querystring is considered the URL component to test against the routes collection

    If the current page URL matches a route, its respective component is activated. See m.component for information on components.

  • m.route.mode

    String mode

    The m.route.mode property defines which URL portion is used to implement the routing mechanism. Its value can be set to either "search", "hash" or "pathname". Default value is "search". Note that if you're changing this configuration value, you should change it before calling m.route.

    • search mode uses the querystring (i.e. ?). This allows named anchors (i.e. <a href="#top">Back to top</a>, <a name="top"></a>) to work on the page, but routing changes causes page refreshes in IE8, due to its lack of support for history.pushState.

      Example URL: http://server/?/path/to/page

    • hash mode uses the hash (i.e. #). It's the only mode in which routing changes do not cause page refreshes in any browser. However, this mode does not support named anchors.

      Example URL: http://server/#/path/to/page

    • pathname mode allows routing URLs that contains no special characters, however this mode requires server-side setup in order to support bookmarking and page refreshes. It always causes page refreshes in IE8.

      Example URL: http://server/path/to/page

      The simplest server-side setup possible to support pathname mode is to serve the same content regardless of what URL is requested. In Apache, this URL rewriting can be achieved using ModRewrite.

      Note that in order to use the pathname mode, the application must be run from the root URL.

  • m.route.param

    String param(String key)

    Route parameters are dynamic values that can be extracted from the URL based on the signature of the currently active route.

    A route without parameters looks like this:


    A route with parameters might look like this:

    "/path/to/page/:id" - here, id is the name of the route parameter

    If the currently active route is /dashboard/:userID and the current URL is /dashboard/johndoe, then calling m.route.param("userID") returns "johndoe"

    Querystring parameters in a route are also available in this collection automatically.

    "/grid?sortby=date" - here, m.route.param("sortby") returns "date"

    • String key

      The name of a route parameter.

    • returns String value

      The value that maps to the parameter specified by key

    Object param()

    • returns Object params

      An object containing all the route parameters

  • m.route.buildQueryString

    String buildQueryString(Object data)

    Serializes an object into its URI encoded querystring representation, following the same serialization conventions as URI.js

    • Object data

      An object to be serialized

    • returns String querystring

      The serialized representation of the input data

  • m.route.parseQueryString

    Object parseQueryString(String querystring)

    Deserializes an object from an URI encoded querystring representation, following the same deserialization conventions as URI.js

    • String querystring

      An URI encoded querystring to be deserialized

    • returns Object data

      The deserialized object



You can programmatically redirect to another page. Given the example in the "Defining Routes" section:


redirects to http://server/#/dashboard/marysue


How to read signatures

void route(String path [, any params] [, Boolean shouldReplaceHistory])
  • String path

    The route to redirect to. Note that to redirect to a different page outside of the scope of Mithril's routing, you should use window.location

  • any params

    Parameters to pass as a querystring

  • Boolean shouldReplaceHistory

    If set to true, replaces the current history entry, instead of adding a new one. Defaults to false.

Reading the currently active route


Mithril updates the native location object after rendering in order to allow the browser's history.pushState API to correctly show descriptive history entries (e.g. for Chrome's Ctrl+H page).

In order to retrieve the currently active route in a controller, you can use m.route(). This returns the portion of the URL determined by m.route.mode (minus the ? or # symbols for the search and hash modes, respectively).

//if the location bar is "http://example.com/?/foo/bar"
//and m.route.mode is `search`
//then `currentRoute == "/foo/bar"`
var currentRoute = m.route();


How to read signatures

String route()
  • returns String route

    returns the currently active route

Mode abstraction


This method is meant to be used with a virtual element's config attribute. For example:

//Note that the '#' is not required in `href`, thanks to the `config` setting.
m("a[href='/dashboard/alicesmith']", {config: m.route});

This makes the href behave correctly regardless of which m.route.mode is selected. It's a good practice to always use the idiom above, instead of hardcoding ? or # in the href attribute.

See m() for more information on virtual elements.


How to read signatures

void route(DOMElement element, Boolean isInitialized, Object context, Object vdom)
  • DOMElement element

    an anchor element <a> with an href attribute that points to a route

  • Boolean isInitialized

    the method does not run if this flag is set to true. This is to make the method compatible with virtual DOM elements' config attribute (see m())

  • Object context

    an object that retains its state across redraws

  • Object vdom

    The virtual DOM data structure to which the config is applied to