Learn how the from function creates observables from arrays, iterables, and promises, emitting synchronously for collections and resolving promises, then completes.

Learn how the startWith operator inserts an initial value before all other emitted events; see how it works with from events and an interval stream.

Test RxJS operators and observable streams using standard unit tests and the RxJS marbles library, with Jest examples. Explore creating input and output marbles, asynchronous testing, and validating prime detection.

Explore practical RxJS scenarios, including error handling, incremental Ajax search with deduplication, periodic API polling, and building a paint-like app or redux-like data store.

Demonstrates incremental search with RxJS by typing to query the GitHub API, throttling requests, filtering empty searches, and handling errors with debounceTime, distinctUntilChanged, switchMap, mergeMap, and catchError.

Enhance the Redux store with RxJS style subscriptions by turning click events into action objects using fromEvent and map, then subscribe the action stream to the store.

Review breaking changes and undocumented behavior in RxJS 7, highlight deprecations heading to RxJS 8, and explain updates for ajax requests, with a focus on maintaining code stability.

Explains the RxJS 6 to 7 change in ajax.getJSON and ajax requests. Notes the x-request-width header can block CORS unless cross-domain is enabled via ajax options.

Discover RxJS 7 updates, including faster execution, reduced memory and bundle size, plus an animation-frame observable, improved TypeScript support, and 7.2’s top-level export of operators.