This concept documents our approach for search engine optimization for the Intershop Progressive Web App.

Server Side Rendering

The PWA uses Universal for pre-rendering complete pages to tackle SEO concerns.
An Angular application without Universal support will not respond to web crawlers with complete indexable page responses.

Angular's state transfer mechanism is used to transfer properties to the client side.
We use it to de-hydrate the ngrx state in the server application and re-hydrate it on the client side.
See Using TransferState API in an Angular v5 Universal App for specifics.

Follow the steps in Guide - Getting Started to build and run the application in Universal mode.

Official documentation for Angular Universal can be found at https://angular.io/guide/universal.

robots.txt

We use the library express-robots-txt in the express.js server (server.ts in the project root) to supply a response to robots.txt for crawlers.

By default the universal server provides a response with access to all pages except some restricted paths (e.g. /error or /account).
To use a custom robots.txt, place it as a file in the dist folder.

Page Metadata

The PWA uses the Meta service for setting tags for title, meta description, robots, canonical links, and open graph infos in page headers.

Meta information can be added to the routing in form of the data property meta.
Have a look at app-routing.module for examples.
It is also possible to use translation keys here.

seo.effects.ts is the central place for customizations concerning dynamic content, e.g., names of products or categories (asynchronous data from the API).
Effects are an essential part of our State Management.

Optimized URLs

Optimized URLs are a major factor in determining search engine rankings.
They should have a clear structure and must be readable.
By default, product, category, and content page routes contain their localized context path.
Parameters are appended to theses paths that contain localization-independent and uniquely identifiable data.

NOTE: The given parameters for each url are needed to differentiate category, product, and content page routes.
It is important to ensure that no identifier contains the specified parameter id.
For example, a category name including a -ctg substring could lead to unwanted behavior.

NOTE: Route generation and parsing for category, product, and content-page routes can be customized.
This will require changes to the well documented product.route.ts, category.route.ts, or content-page.route.ts files.
Additionally, the corresponding pipes (e.g., product-route.pipe.ts) may have to be updated to fit your needs as will routing.ts.