spa-router-vir

The heroic, type safe, frontend router for any modern Single Page Application (SPA).

It works by hooking into window.history.pushState and window.history.replaceState.

Install

Install via npm:

npm i spa-router-vir

Examples

• The GitHub repo for this package contains an example which can be tested using npm start.
• The threejs-experiments repo utilizes this package.

Usage

Creating a Router

Create a router by constructing SpaRouter. Ensure that you only ever have a single active router at a time. You must provide a sanitizeRoute callback for ensuring that run-time routes actually match your required route types.

Here is an example usage of SpaRouter with full run-time route type safety:

import {FullRoute, SpaRouter} from 'spa-router-vir';

export const myRouter = new SpaRouter<
    /** The allowed router paths. */
    ValidRouterPaths,
    /** This router does not allow _any_ search params. */
    undefined,
    /** This router does not allow _any_ hash string. */
    undefined
>({
    /**
     * `sanitizeRoute` is required and is the only way to ensure route type safety at run-time. This
     * ensures that all URLs navigated to from within your SPA are valid and handled by your
     * application.
     */
    sanitizeRoute(rawRoute) {
        return {
            paths: sanitizePaths(rawRoute),
            search: undefined,
            hash: undefined,
        };
    },
});

/**
 * Example valid paths that allow the following website URL paths:
 *
 * - `/home`
 * - `/gallery/<any-string>`
 * - `/about`
 * - `/about/team`
 * - `/about/website`
 */
export type ValidRouterPaths =
    | ['home']
    | ['gallery', /** Specific gallery id. */ string]
    | ['about']
    | ['about', 'team' | 'website'];

/** A helper function that specifically sanitizes the `paths` part of the route. */
export function sanitizePaths(rawRoute: Readonly<Pick<FullRoute, 'paths'>>): ValidRouterPaths {
    const topLevelPath = rawRoute.paths[0];

    if (topLevelPath === 'about') {
        if (rawRoute.paths[1] !== 'team' && rawRoute.paths[1] !== 'website') {
            return ['about'];
        } else {
            return [
                'about',
                rawRoute.paths[1],
            ];
        }
    } else if (topLevelPath === 'gallery' && rawRoute.paths[1]) {
        return [
            'gallery',
            rawRoute.paths[1],
        ];
    } else {
        /** Default to this route. */
        return ['home'];
    }
}

Supporting SPAs on GitHub Pages (or other similar services)

To use SpaRouter on GitHub Pages, you must set a basePath property when constructing SpaRouter. This ensures that your GitHub Pages repo path is maintained:

import {SpaRouter} from 'spa-router-vir';
import {ValidRouterPaths, sanitizePaths} from './router-creation.example';

export const myRouter = new SpaRouter<
    /** Use the same route type parameters as the earlier example for simplicity. */
    ValidRouterPaths,
    undefined,
    undefined
>({
    /** Sue the same route sanitizer as the earlier example for simplicity. */
    sanitizeRoute(rawRoute) {
        return {
            paths: sanitizePaths(rawRoute),
            search: undefined,
            hash: undefined,
        };
    },
    basePath: 'my-repo',
});

You can see this in action on the threejs-experiments example demo. Notice that threejs-experiments is always the first path and it does not mess up the router.

In addition to setting the router up, to get a SPA to work on GitHub Pages you need to copy paste your index.html and rename the copy to 404.html in the top-level of your GitHub Pages deployed directory. That is done in threejs-experiments as part of the deploy pipeline script.

Listening to route changes

Use listen to listen to route changes. When true, the first parameter (which is called fireImmediately) will force your router to immediately call the given listener callback. This prevents the need to manually call your own callback to update route-specific content on first page load.

import {myRouter} from './router-creation.example';

myRouter.listen(true, (routes) => {
    console.info(routes);
});

Listeners can be removed with the removeListener() method, or by calling the return value of .listen():

import {FullRoute} from 'spa-router-vir';
import {myRouter, ValidRouterPaths} from './router-creation.example';

/** Remove a listener with the removal callback. */
{
    const removeListener = myRouter.listen(true, (route) => {
        console.info(route);
    });

    removeListener();
}

/** Remove a listener by keeping track of it and passing it in to `removeListener`. */
{
    function listenToRoute(route: FullRoute<ValidRouterPaths, undefined, undefined>) {
        console.info(route);
    }

    myRouter.listen(true, listenToRoute);

    myRouter.removeListener(listenToRoute);
}

Creating a URL for links

To create a single URL string for any given route, use the createRouteUrl() method. This will create a URL that takes the SpaRouter's basePath into account, if it's provided, so you don't have to manually handle that yourself.

import {myRouter} from './router-creation.example';

document.getElementsByTagName('a')[0]!.href = myRouter.createRouteUrl({
    paths: [
        'gallery',
        'gallery-id-here',
    ],
});

Navigating Routes

To navigate to a new route, use the .setRoute() method. This will first sanitize your route, ensure that it properly includes basePath, and set it to the window URL:

import {myRouter} from './router-creation.example';

myRouter.setRoute({
    paths: [
        'gallery',
        'another-gallery-id',
    ],
});

Note that you can also use the method .setRouteOnDirectNavigation() to navigate to routes only if a given MouseEvent allows direct navigation. (Meaning, only if the user didn't try to open a link in a new tab or right click on the link.)