2.4.17 • Public • Published

A router for Seemple.js

npm version



npm install seemple-router

A bundle (downloadable version) lives at gh-pages branch


The library turns on two-way data binding between properties and parts of URL.

// location.hash is used there
Seemple.initRouter(object, '/a/b/c/');
object.a = 'foo';
object.b = 'bar';
object.c = 'baz';
// makes location.hash to be #!/foo/bar/baz/

If you need to use History API instead of hash, pass "history" as the second argument.

Seemple.initRouter(object, '/a/b/c/', 'history');

CJS module import:

const initRouter = require('seemple-router');
initRouter(object, '/a/b/c/', 'history');

How does "traditional" routing works? A developer defines a rule (route) and defines a function which will be called when current path fits given rule.

route("books/:id", id => {
    // do something

The principle of seemple-router is different. You define which part of URL (both hash, and HTML5 History are supported) need to be synchronized with given property.

Let's say you need to synchronize "x" with the first part of location.hash and "y" with the second.

Seemple.initRouter(object, '/x/y/');

Now when you type...

object.x = 'foo';
object.y = 'bar';

...location.hash is automatically changed to #!/foo/bar/

And vice versa. When the URL is changed manually or via back and forward buttons, the properties will be changed automatically.

location.hash = '#!/baz/qux/';
// ... after a moment
console.log(object.x, object.y); // ‘baz’, ‘qux’

As usually you can listen property changes with Seemple#on method.

Seemple.on(object, 'change:x', handler);
// for Seemple instances: this.on('change:x', handler);

An asterisk syntax

You can pass a string which contain asterisks to initRouter if you don't need to synchronize some part of the path with a property.

Seemple.initRouter(object, '/x/*/y');

If the hash looks like #!/foo/bar/baz/, then this.x = "foo" and this.y = "baz".

This feature is useful in cases when classes control different parts of the path.


Seemple.initRouter(this, '/x/*/');


Seemple.initRouter(this, '/*/y/');

Two things to remember

1. If a property has truthy value then URL will be changed immediately after initRouter call.

object.x = 'foo';
Seemple.initRouter(object, '/x/y/');

2. If a property gets falsy value then all next listed properties will get null as new value.

Seemple.initRouter(object, '/x/y/z/u/');
Seemple.y = null; // makes this.z and this.u to be null as well

The idea is to get actual state of URL. It could be weird to get "z" with value "foo" in case of non-existing bound part of URL.

HTML5 History API

The plugin supports HTML5 History as well. To initialize it you need to pass optional argument type with "history" value to the initRoute function (by default type is "hash").

Seemple.initRouter(object, 'x/y/z/', 'history');

CommonJS import

If an application is located at CJS environment (NodeJS, Webpack, Rollup...) then requiring seemple-router doesn't add any static properties to Seemple class.

const initRouter = require('seemple-router');
initRouter(object, '/x/y/');

Router class import (read below):

const Router = require('seemple-router/router');
const customRouter = new Router('myType');

Additional information

Seemple.Router class

seemple-router is powered by Seemple.Router class. It accepts only one argument - router type ("hash", "history" or a custom string).

By default, the library creates two instances of Seemple.Router with types hash and history. They live at Seemple.Router.hash and Seemple.Router.history. seemple-router uses lazy initialization so when you just attach the script onto webpage, the library does nothing.

For these two types of instances the singleton pattern is used. That means when you're trying to create another instance of hash routing via new Seemple.Router('hash'), the Seemple.Router.hash will be returned instead of new instance creation. This logic centralizes URL handling, gives positive effect to the performance and doesn't make potential collisions. Objects which are handled by initRouter just subscribe to the changes of needed type of the router.

Custom instances (non-hash and non-history) of Seemple.Router can be created manually in case if you generate URL for further use. At this case changes of target properties don't affect on hash and don't call pushState.


Seemple.Router instances has 3 properties.

  • path - contains actual URL, eg /foo/bar/baz/.
  • hashPath - contains actual URL and hashbang as a prefix, eg #!/foo/bar/baz/
  • parts - contains an array of all parts of the path, eg [‘foo’, ‘bar’, ‘baz’].

All these properties are created using calc, which means when you change one property, the others are changed automatically.

Seemple.Router.hash.path = '/foo/bar/baz/';

By changing these properties you can trigger needed procedures (update the path, change subscribed objects etc.)


  • subscribe(object, route) - subscribes object for route changes.
  • init() - used for lazy initialization in subscribe method (no need to call it manually).
const customRouter = new Seemple.Router('myType');
const object = {
    a: 'foo',
    b: 'bar'
customRouter.subscribe(object, '/a/b/');
console.log(customRouter.path); // /foo/bar/



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