# Path Syntax

{% hint style="info" %}
*router5* uses [path-parser](https://github.com/troch/path-parser) for parsing, matching and generating URLs
{% endhint %}

## Defining parameters

Four parameter types are supported:

* `:param`: url parameters
* `;matrix`: matrix parameters
* `*splat`: for parameters spanning over multiple segments. Splat parameters are greedy and could swallow a

  large part of your URL. It is recommended to handle with care and to ONLY use on routes without children.
* `?param1&param2` or `?:param1&:param2`: query parameters

## Constrained parameters

Url and matrix parameters can be constrained with a regular expression. Backslashes need to be escaped.

* `:param<\\d+>` will match numbers only for parameter param
* `;id<[a-fA-F0-9]{8}>` will match 8 characters hexadecimal strings for parameter id

Constraints are also applied when building paths: when passing incorrect params to `.navigate()`, an error will be thrown.

## Absolute nested paths

You can define absolute nested paths (not concatenated with their parent's paths). Note that absolute paths are not allowed if any parent of a node has parameters.

```javascript
const router = createRouter([
    { name: 'admin', path: '/admin' },
    { name: 'admin.users', path: '~/users' }
]);

router.buildPath('admin.users'); // '/users'
```