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This package provides the means to statically represent routes, which helps establish a single source of truth for generating links inside an application.

💡 This library works best with TypeScript.

• 📦 npm: npm i route-descriptor

Routes are created by calling the route(...) function with the route's path and a type that encapsulates its parameters. This returns another function which can be further evaluated against a specific set of route parameters to resolve the matching URL.

Static routes are routes that have no parameters and, as a result, always resolve to the same URL. To create a descriptor for a static route, call route(...) with just the route's path:

import { route } from 'route-descriptor';

const home = route('/home');

const href = home(); // '/home'

Dynamic routes can resolve to different URLs depending on the specified parameters. In order to create a descriptor for a dynamic route, call route(...) with a path template and a generic argument that defines the parameters it can accept:

import { route } from 'route-descriptor';

interface ProductParams {
  id: number;
}

const product = route<ProductParams>('/products/:id');

const href = product({ id: 3 }); // '/products/3'

To resolve the URL, the descriptor will try to match the parameter names with placeholders in the path template. If some of the parameters don't match with any of the placeholders, they will be added as query parameters instead:

import { route } from 'route-descriptor';

interface ProductParams {
  id: number;
  showComments?: boolean;
}

const product = route<ProductParams>('/products/:id');

const href = product({
  id: 3,
  showComments: true
}); // '/products/3?showComments=true'

Once descriptor is created, it's possible to retrieve its path template by accessing the path field:

import { route } from 'route-descriptor';

const profile = route<ProfileParams>('/profile/:id/:name?');

const path = profile.path; // '/profile/:id/:name?'

This package can be used in combination with practically any client-side routing library. For example, here is how to integrate it with React Router:

• ./src/routes.ts:

// This module serves as a single source of truth for routing

import { route } from 'route-descriptor';

interface ProductParams {
  id: number;
  showComments?: boolean;
}

interface ProfileParams {
  id: number;
  name?: string;
}

export default {
  home: route('/home'),
  product: route<ProductParams>('/products/:id'),
  profile: route<ProfileParams>('/profile/:id/:name?')
};

• ./src/App.tsx:

import { Route, Switch, BrowserRouter, Link } from 'react-router-dom';
import routes from './routes';

function Home() {
  // To resolve route link, pass the parameters that the route expects
  
  return (
    <div>
      <Link to={routes.home()}>Home</Link>
      <Link to={routes.profile({ id: 1, name: 'JohnDoe' })}>My Profile</Link>
      <Link to={routes.product({ id: 3, showComments: true })}>Random Product</Link>
    </div>
  );
}

function Product() {
  /* ... */
}

function Profile() {
  /* ... */
}

export default function App() {
  // We can use the `path` field to retrieve the original
  // path template and feed it to react-router.

  return (
    <BrowserRouter>
      <Switch>
        <Route path={routes.profile.path} component={Profile} />
        <Route path={routes.product.path} component={Product} />
        <Route path={routes.home.path} component={Home} />
      </Switch>
    </BrowserRouter>
  );
}

This package is most useful when paired with TypeScript, as it provides static validation for parameters. For example, all of the following incorrect usages produce errors during compilation:

import { route } from 'route-descriptor';

const home = route('/home');

home({ id: 5 }); // <- error (static route can't accept parameters)

// ----

interface ProductParams {
  id: number;
  showComments?: boolean;
}

const product = route<ProductParams>('/products/:id');

product(); // <- error (dynamic route requires parameters)
product({ showComments: true }); // <- error (missing 'id')
product({ id: 3, name: 'apple' }); // <- error (unexpected 'name')