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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  • Arguments
  • Returns
  • Example
  • Without key selector
  • With key selector

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  1. Summary
  2. Observable
  3. Observable Instance Methods

distinct

Returns an observable sequence that contains only distinct elements according to the keySelector and the comparer. Usage of this operator should be considered carefully due to the maintenance of an internal lookup structure which can grow large.

Arguments

  1. [keySelector] (Function): A function to compute the comparison key for each element.

  2. [keySerializer] (Function): Used to serialize the given object into a string for object comparison.

Returns

(Observable): An observable sequence only containing the distinct elements, based on a computed key value, from the source sequence.

Example

Without key selector

With key selector

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Last updated 5 years ago

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