RxJs Book
  • Introduction
  • Summary
    • Why RxJS?
    • RxJS Design Guidelines
      • Introduction
      • When To Use RxJS
      • The RxJS Contract
      • Using RxJS
      • Operator Implementations
    • Getting Started With RxJS
      • What Are The Reactive Extensions?
      • Exploring Major Concepts In RxJS
      • Creating And Querying Observable Sequences
        • Creating And Subscribing To Simple Observable Sequences
        • Bridging To Events
        • Bridging To Callbacks
        • Bridging To Promises
        • Generators And Observable Sequences
        • Querying Observable Sequences
        • Error Handling With Observable Sequences
        • Transducers With Observable Sequences
        • Backpressure With Observable Sequences
        • Operators By Category
      • Subjects
      • Scheduling And Concurrency
      • Testing And Debugging
      • Implementing Your Own Operators
    • How Do I...?
      • How Do I Wrap An Existing API?
      • How Do I Integrate jQuery With RxJS?
      • How Do I Integrate Angular.js With RxJS?
      • How Do I Create A Simple Event Emitter?
    • Mapping RxJS From Different Libraries
      • For Bacon.js Users
      • For Async.js Users
    • Config
      • Promise
      • useNativeEvents
    • Helpers
      • defaultComparer
      • defaultSubComparer
      • defaultError
      • identity
      • just
      • isPromise
      • noop
      • pluck
    • Observable
      • Observable Methods
        • amb
        • case
        • catch
        • combineLatest
        • concat
        • create
        • defer
        • empty
        • for | forIn
        • forkJoin
        • from
        • fromCallback
        • fromEvent
        • fromEventPattern
        • fromNodeCallback
        • fromPromise
        • generate
        • generateWithAbsoluteTime
        • generateWithRelativeTime
        • if
        • interval
        • isObservable
        • just | return
        • merge
        • mergeDelayError
        • never
        • of
        • ofWithScheduler
        • onErrorResumeNext
        • pairs
        • range
        • repeat
        • spawn
        • start
        • startAsync
        • throw
        • timer
        • toAsync
        • using
        • when
        • while | whileDo
        • wrap
        • zip
      • Observable Instance Methods
        • amb
        • and
        • asObservable
        • average
        • buffer
        • bufferWithCount
        • bufferWithTime
        • bufferWithTimeOrCount
        • catch
        • combineLatest
        • concat
        • concatAll
        • concatMapObserver | selectConcatObserver
        • controlled
        • count
        • debounce
        • defaultIfEmpty
        • delay
        • delaySubscription
        • dematerialize
        • distinct
        • distinctUntilChanged
        • do | doAction | tap
        • doOnCompleted | tapOnCompleted
        • doOnError | tapOnError
        • doOnNext | tapOnNext
        • doWhile
        • elementAt
        • every
        • expand
        • extend | manySelect
        • filter | where
        • finally
        • find
        • findIndex
        • first
        • flatMap | selectMany
        • flatMapConcat | concatMap
        • flatMapFirst | selectSwitchFirst
        • flatMapLatest
        • flatMapObserver | selectManyObserver
        • flatMapWithMaxConcurrent
        • forkJoin
        • groupBy
        • groupByUntil
        • groupJoin
        • ignoreElements
        • includes
        • indexOf
        • isEmpty
        • join
        • jortSort
        • jortSortUntil
        • last
        • lastIndexOf
        • let | letBind
        • map | select
        • materialize
        • max
        • maxBy
        • merge
        • mergeAll
        • min
        • minBy
        • multicast
        • observeOn
        • onErrorResumeNext
        • pairwise
        • partition
        • pausable
        • pausableBuffered
        • pipe
        • pluck
        • publish
        • publishLast
        • publishValue
        • reduce
        • repeat
        • replay
        • retry
        • retryWhen
        • scan
        • sequenceEqual
        • share
        • shareReplay
        • shareValue
        • single
        • singleInstance
        • skip
        • skipLast
        • skipLastWithTime
        • skipUntil
        • skipUntilWithTime
        • skipWhile
        • skipWithTime
        • slice
        • some
        • startWith
        • subscribe | forEach
        • subscribeOn
        • subscribeOnCompleted
        • subscribeOnError
        • subscribeOnNext
        • sum
        • switch
        • switchFirst
        • take
        • takeLast
        • takeLastBuffer
        • takeLastBufferWithTime
        • takeLastWithTime
        • takeUntil
        • takeUntilWithTime
        • takeWhile
        • takeWithTime
        • thenDo
        • throttle
        • throttleLatest | sample
        • timeInterval
        • timeout
        • timestamp
        • toArray
        • toMap
        • toPromise
        • toSet
        • transduce
        • window
        • windowWithCount
        • windowWithTime
        • windowWithTimeOrCount
        • withLatestFrom
        • zip
        • zipIterable
    • Observer
      • Observer Methods
        • create
        • fromNotifier
      • Observer Instance Methods
        • asObserver
        • checked
        • notifyOn
        • onCompleted
        • onError
        • onNext
        • toNotifier
    • Notification
      • Notification Methods
        • createOnNext
        • createOnError
        • createOnCompleted
      • Notification Instance Methods
        • accept
        • toObservable
      • Notification Properties
        • exception
        • hasValue
        • kind
        • value
    • Subjects
      • Rx.AsyncSubject
      • Rx.BehaviorSubject
      • Rx.ReplaySubject
      • Rx.Subject
    • Schedulers
      • Rx.HistoricalScheduler
      • Rx.Scheduler
      • Rx.VirtualTimeScheduler
    • Disposables
      • Rx.CompositeDisposable
      • Rx.Disposable
      • Rx.RefCountDisposable
      • Rx.SerialDisposable
      • Rx.SingleAssignmentDisposable
    • Testing
      • Rx.ReactiveTest
      • Rx.Recorded
      • Rx.Subscription
      • Rx.TestScheduler
    • Bindings
      • DOM
        • Ajax
          • ajax
          • ajaxCold
          • get
          • get_Json
          • post
        • JSONP
          • jsonpRequest
          • jsonpRequestCold
        • Web Sockets
          • fromWebSocket
        • Web Workers
          • fromWebWorker
        • Mutation Observers
          • fromMutationObserver
        • Geolocation
          • getCurrentPosition
          • watchPosition
        • Schedulers
          • requestAnimationFrame
          • mutationObserver
      • jQuery
      • AngularJS
        • Factories
          • rx
          • observeOnScope
        • Observable Methods
          • safeApply
        • $rootScope Methods
          • $toObservable
          • $eventToObservable
          • $createObservableFunction
      • Facebook React
      • Ractive.js
      • Node.js
        • Callback Handlers
          • fromCallback
          • fromNodeCallback
        • Event Handlers
          • fromEvent
          • toEventEmitter
        • Stream Handlers
          • fromStream
          • fromReadableStream
          • fromWritableStream
          • fromTransformStream
          • writeToStream
  • Recipes
  • Which Operator do I use?
    • Creation Operators
    • Instance Operators
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  • Returns
  • Example

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  1. Summary
  2. Observable
  3. Observable Instance Methods

reduce

Applies an accumulator function over an observable sequence, returning the result of the aggregation as a single element in the result sequence. The specified seed value is used as the initial accumulator value.

For aggregation behavior with incremental intermediate results, see the scan method.

Arguments

  1. accumulator (Function): An accumulator function to be invoked on each element.

  2. [seed] (Any): The initial accumulator value.

Returns

(Observable): An observable sequence containing a single element with the final accumulator value.

Example

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Last updated 5 years ago

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