@rx-angular/isr

A library that enables Angular Universal applications to generate static pages at runtime and then update them incrementally on demand or on a schedule.

Features

• ⏰ Scheduled cache invalidation
• ▶️ On-demand cache invalidation
• 🔌 Plugin based cache handlers
• 👌 No build changes required!
• 🅰️ Supports Angular Universal
• 🛡️ NgModules & Standalone Compatible

Installation

npm install @rx-angular/isr

Version Compatibility

RxAngular	Angular
^18.0.0	^18.0.0
^17.1.0	^17.0.0
^16.0.0	^16.0.0

How to use it?

1. Initialize ISRHandler inside server.ts

const isr = new ISRHandler({
  indexHtml,
  invalidateSecretToken: 'MY_TOKEN', // replace with env secret key ex. process.env.REVALIDATE_SECRET_TOKEN
  enableLogging: !environment.production,
});

2. Add invalidation url handler

server.use(express.json());
server.post('/api/invalidate', async (req, res) => await isr.invalidate(req, res));

3. Replace Angular default server side rendering with ISR rendering

Replace

server.get('*', (req, res) => {
  res.render(indexHtml, {
    req,
    providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }],
  });
});

with

server.get(
  '*',
  // Serve page if it exists in cache
  async (req, res, next) => await isr.serveFromCache(req, res, next),
  // Server side render the page and add to cache if needed
  async (req, res, next) => await isr.render(req, res, next),
);

You can also pass providers to each of the ISRHandler methods.

server.get(
  '*',
  ...async (req, res, next) =>
    await isr.render(req, res, next, {
      providers: [
        { provide: APP_BASE_HREF, useValue: req.baseUrl }, // <-- Needs to be provided when passing providers
        { provide: CUSTOM_TOKEN, useValue: 'Hello from ISR' },
        CustomService,
      ],
    }),
);

It is also possible to pass a modifyCachedHtml or modifyGeneratedHtml callbacks to the ISRHandler methods. These methods provide a way to modify the html served from cache or the html that is generated on the fly.

Important: Use these methods with caution as the logic written can increase the processing time.

server.get(
  '*',
  // Serve page if it exists in cache
  async (req, res, next) =>
    await isr.serveFromCache(req, res, next, {
      modifyCachedHtml: (req, cachedHtml) => {
        return `${cachedHtml}<!-- Hello, I'm a modification to the original cache! -->`;
      },
    }),
  // Server side render the page and add to cache if needed
  async (req, res, next) =>
    await isr.render(req, res, next, {
      modifyGeneratedHtml: (req, html) => {
        return `${html}<!-- Hello, I'm modifying the generatedHtml before caching it! -->`;
      },
    }),
);

ISRHandler provides APP_BASE_HREF by default. And if you want pass providers into the methods of ISRHandler, you will also have to provide APP_BASE_HREF token.

4. Add revalidate key in route data

Example:

{
  path: "example",
  component: ExampleComponent,
  data: { revalidate: 5 },
}

NOTE: Routes that don't have revalidate key in data won't be handled by ISR. They will fallback to Angular default server side rendering pipeline.

5. Register providers To register the ISR providers, you can either import IsrModule in your AppServerModule or provide provideISR in your AppServerModule providers.

Or, if you are in a standalone app, you can register the providers in your app.config.server.ts file.

• Register using IsrModule

import { IsrModule } from '@rx-angular/isr/server'; // <-- Import module from library

@NgModule({
  imports: [
    IsrModule.forRoot(), // <-- Use it in module imports
  ],
})
export class AppServerModule {}

• Register using the provideISR function

import { provideISR } from '@rx-angular/isr/server';

@NgModule({
  providers: [
    provideISR(), // <-- Use it in module providers
  ],
})
export class AppServerModule {}

• Register using the provideISR function in standalone app

import { provideISR } from '@rx-angular/isr/server';

const serverConfig: ApplicationConfig = {
  providers: [
    provideServerRendering(),
    provideISR(), // <-- Use it in config providers
  ],
};

When registering the providers, IsrService will be initialized and will start to listen to route changes, only on the server side, so the browser bundle won't contain any extra code.

License

MIT

All-in-One library

ISR provides everything you need to speed up your Angular Universal app.

Scheduled cache invalidation

@rx-angular/isr provides a simple API to invalidate the cache based on a schedule. Requests are not cached by default. You have to explicitly mark the routes you want to cache.

On-demand cache invalidation

Revalidate specific routes on demand, when you need to and not based on a schedule. This is useful when you need to invalidate the cache when a user performs an action.

Plugin based cache handlers

Cache handlers are pluggable, allowing the cache to be stored in different locations. It provides a default cache handler that stores the cache in memory.

No build changes required!

Easy to setup and use and also no changes to your build process are required.

Supports Angular Universal

Compatible with Angular Universal is used as a plugin for the Angular Universal platform.

NgModules & Standalone Compatible

Supports both NgModules and standalone use. You can use it in your existing Angular project.