Wednesday, 31 October 2018

RXJS Operators

Operators By Category

1- Creating Observables

Operators that originate new Observables.
  • Create — create an Observable from scratch by calling observer methods programmatically
  • Defer — do not create the Observable until the observer subscribes, and create a fresh Observable for each observer
  • Empty/Never/Throw — create Observables that have very precise and limited behavior
  • From — convert some other object or data structure into an Observable
  • Interval — create an Observable that emits a sequence of integers spaced by a particular time interval
  • Just — convert an object or a set of objects into an Observable that emits that or those objects
  • Range — create an Observable that emits a range of sequential integers
  • Repeat — create an Observable that emits a particular item or sequence of items repeatedly
  • Start — create an Observable that emits the return value of a function
  • Timer — create an Observable that emits a single item after a given delay

2- Transforming Observables

Operators that transform items that are emitted by an Observable.
  • Buffer — periodically gather items from an Observable into bundles and emit these bundles rather than emitting the items one at a time
  • FlatMap — transform the items emitted by an Observable into Observables, then flatten the emissions from those into a single Observable
  • GroupBy — divide an Observable into a set of Observables that each emit a different group of items from the original Observable, organized by key
  • Map — transform the items emitted by an Observable by applying a function to each item
  • Scan — apply a function to each item emitted by an Observable, sequentially, and emit each successive value
  • Window — periodically subdivide items from an Observable into Observable windows and emit these windows rather than emitting the items one at a time

3- Filtering Observables

Operators that selectively emit items from a source Observable.
  • Debounce — only emit an item from an Observable if a particular timespan has passed without it emitting another item
  • Distinct — suppress duplicate items emitted by an Observable
  • ElementAt — emit only item n emitted by an Observable
  • Filter — emit only those items from an Observable that pass a predicate test
  • First — emit only the first item, or the first item that meets a condition, from an Observable
  • IgnoreElements — do not emit any items from an Observable but mirror its termination notification
  • Last — emit only the last item emitted by an Observable
  • Sample — emit the most recent item emitted by an Observable within periodic time intervals
  • Skip — suppress the first n items emitted by an Observable
  • SkipLast — suppress the last n items emitted by an Observable
  • Take — emit only the first n items emitted by an Observable
  • TakeLast — emit only the last n items emitted by an Observable

4- Combining Observables

Operators that work with multiple source Observables to create a single Observable
  • And/Then/When — combine sets of items emitted by two or more Observables by means of Patternand Plan intermediaries
  • CombineLatest — when an item is emitted by either of two Observables, combine the latest item emitted by each Observable via a specified function and emit items based on the results of this function
  • Join — combine items emitted by two Observables whenever an item from one Observable is emitted during a time window defined according to an item emitted by the other Observable
  • Merge — combine multiple Observables into one by merging their emissions
  • StartWith — emit a specified sequence of items before beginning to emit the items from the source Observable
  • Switch — convert an Observable that emits Observables into a single Observable that emits the items emitted by the most-recently-emitted of those Observables
  • Zip — combine the emissions of multiple Observables together via a specified function and emit single items for each combination based on the results of this function

5- Error Handling Operators

Operators that help to recover from error notifications from an Observable
  • Catch — recover from an onError notification by continuing the sequence without error
  • Retry — if a source Observable sends an onError notification, resubscribe to it in the hopes that it will complete without error

6- Observable Utility Operators

A toolbox of useful Operators for working with Observables
  • Delay — shift the emissions from an Observable forward in time by a particular amount
  • Do — register an action to take upon a variety of Observable lifecycle events
  • Materialize/Dematerialize — represent both the items emitted and the notifications sent as emitted items, or reverse this process
  • ObserveOn — specify the scheduler on which an observer will observe this Observable
  • Serialize — force an Observable to make serialized calls and to be well-behaved
  • Subscribe — operate upon the emissions and notifications from an Observable
  • SubscribeOn — specify the scheduler an Observable should use when it is subscribed to
  • TimeInterval — convert an Observable that emits items into one that emits indications of the amount of time elapsed between those emissions
  • Timeout — mirror the source Observable, but issue an error notification if a particular period of time elapses without any emitted items
  • Timestamp — attach a timestamp to each item emitted by an Observable
  • Using — create a disposable resource that has the same lifespan as the Observable

7- Conditional and Boolean Operators

Operators that evaluate one or more Observables or items emitted by Observables
  • All — determine whether all items emitted by an Observable meet some criteria
  • Amb — given two or more source Observables, emit all of the items from only the first of these Observables to emit an item
  • Contains — determine whether an Observable emits a particular item or not
  • DefaultIfEmpty — emit items from the source Observable, or a default item if the source Observable emits nothing
  • SequenceEqual — determine whether two Observables emit the same sequence of items
  • SkipUntil — discard items emitted by an Observable until a second Observable emits an item
  • SkipWhile — discard items emitted by an Observable until a specified condition becomes false
  • TakeUntil — discard items emitted by an Observable after a second Observable emits an item or terminates
  • TakeWhile — discard items emitted by an Observable after a specified condition becomes false

8- Mathematical and Aggregate Operators

Operators that operate on the entire sequence of items emitted by an Observable
  • Average — calculates the average of numbers emitted by an Observable and emits this average
  • Concat — emit the emissions from two or more Observables without interleaving them
  • Count — count the number of items emitted by the source Observable and emit only this value
  • Max — determine, and emit, the maximum-valued item emitted by an Observable
  • Min — determine, and emit, the minimum-valued item emitted by an Observable
  • Reduce — apply a function to each item emitted by an Observable, sequentially, and emit the final value
  • Sum — calculate the sum of numbers emitted by an Observable and emit this sum

9- Backpressure Operators

  • backpressure operators — strategies for coping with Observables that produce items more rapidly than their observers consume them

10- Connectable Observable Operators

Specialty Observables that have more precisely-controlled subscription dynamics
  • Connect — instruct a connectable Observable to begin emitting items to its subscribers
  • Publish — convert an ordinary Observable into a connectable Observable
  • RefCount — make a Connectable Observable behave like an ordinary Observable
  • Replay — ensure that all observers see the same sequence of emitted items, even if they subscribe after the Observable has begun emitting items

11- Operators to Convert Observables

  • To — convert an Observable into another object or data structure

To read more about http://reactivex.io/




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