rou3 library in Nitro codebase.

#rou3 #nitro #render #opensource

In this article, we review rou3 library in Nitro codebase. We will look at:

What is rou3 library?
rou3 library in Nitro.

I study patterns used in an open source project found on Github Trending. For this week, I reviewed some parts of Nitro codebase and wrote this article.

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What is rou3 library?

Lightweight and fast rou(ter) for JavaScript.

Install

# ✨ Auto-detect
npx nypm install rou3

Create a router instance and insert routes:

import { createRouter, addRoute } from "rou3";

const router = createRouter(/* options */);

addRoute(router, "GET", "/path", { payload: "this path" });
addRoute(router, "POST", "/path/:name", { payload: "named route" });
addRoute(router, "GET", "/path/foo/**", { payload: "wildcard route" });
addRoute(router, "GET", "/path/foo/**:name", {
  payload: "named wildcard route",
});

Match route to access matched data:

// Returns { payload: 'this path' }
findRoute(router, "GET", "/path");

// Returns { payload: 'named route', params: { name: 'fooval' } }
findRoute(router, "POST", "/path/fooval");

// Returns { payload: 'wildcard route' }
findRoute(router, "GET", "/path/foo/bar/baz");

// Returns undefined (no route matched for/)
findRoute(router, "GET", "/");

rou3 library in Nitro.

At L13 in prerender.ts file, you will find the below import:

import { createRouter, addRoute, findAllRoutes } from "rou3";

and below is how prerender creates routes, found at L113:

// Create route rule matcher
const routeRules = createRouter<NitroRouteRules>();
for (const [route, rules] of Object.entries(nitro.options.routeRules)) {
  addRoute(routeRules, undefined, route, rules);
}

findAllRoutes is called in _getRouteRules function.

const _getRouteRules = (path: string) =>
  defu(
    {},
    ...findAllRoutes(routeRules, undefined, path)
      .map((r) => r.data)
      .reverse()
  ) as NitroRouteRules;