Angular `Observables` notes

angular_notes.md

Angular Observables notes

https://angular.io/guide/rx-library

• A promise can be subcribed.
• It will give an observable.

const secondsCounter = interval(1000);
secondsCounter.subscribe(n =>
  console.log(`It's been ${n} seconds since subscribing!`));

• You can use multiple built-in Operators on observable
  • The map() method creates a new array with the results of calling a provided function on every element in the calling array.
  • The filter() method creates a new array with all elements that pass the test implemented by the provided function.
• You can use pipes to link operators together.

const squareOdd = of(1, 2, 3, 4, 5)
  .pipe(
    filter(n => n % 2 !== 0),
    map(n => n * n)
  );

• RxJS provides the catchError operator that lets you handle known errors in the observable recipe.

Operators

• Creation from, fromPromise,fromEvent, of
• Combination combineLatest, concat, merge, startWith , withLatestFrom, zip
• Filtering debounceTime, distinctUntilChanged, filter, take, takeUntil
• Transformation bufferTime, concatMap, map, mergeMap, scan, switchMap
• Utility tap
• Multicasting share