By Fresh authors

The /about route created on the last page is pretty static. It does not matter what query or path parameters are passed to the route, it will always render the same page. Let's create a /greet/:name that will render a page with a greeting that contains the name passed in the path.

Before diving in, a quick refresher on "dynamic" routes. Dynamic routes don't just match a single static path, but rather a whole bunch of different paths based on a pattern. For example, the /greet/:name route will match the paths /greet/Luca and /greet/John, but not /greet or /greet/Luca/John.

Fresh supports dynamic routes out of the box through file system routing. To make any path segment dynamic, just put square brackets around that segment in the file name. For example the /greet/:name route maps to the file name routes/greet/[name].tsx.

Just like the static /about route, the dynamic /greet/:name route will render a page. The module must once again expose a component as a default export. This time the component will receive the matched path segment properties as arguments in it's props object though.

// routes/greet/[name].tsx

/** @jsx h */
import { h } from "preact";
import { PageProps } from "$fresh/server.ts";

export default function GreetPage(props: PageProps) {
  const { name } = props.params;
  return (
    <main>
      <p>Greetings to you, {name}!</p>
    </main>
  );
}

The PageProps interface actually contains a bunch of useful properties that can be used to customize the rendered output. Next to the matched url pattern parameters, the raw url, and the route name can also be found in here.

Navigating to https://localhost:8000/greet/Luca will now render a page showing "Greetings to you, Luca!".

The Concepts: Routing page has more information about dynamic routes, especially about how to create more advanced dynamic routes.