How can I create an observable with a delay

Question

Question  For testing purposes  I m creating Observable objects that replace the observable that would be returned by an actual http call with Http   My observable is created with the following code   fakeObservable   Observable create obs   gt      obs next  1  2  3      obs complete          The thing is  this observable emits immediatly  Is there a way to add a custom delay to its emission     Track  I tried this   fakeObservable   Observable create obs   gt      setTimeout      gt        obs next  1  2  3        obs complete         100         But it doesn t seem to work

User · Answer

It s little late to answer     but just in case may be someone return to this question looking for an answer   delay  is property function  of an Observable  fakeObservable   Observable create obs   gt      obs next  1  2  3      obs complete       delay 3000     This worked for me

User · Answer

In RxJS 5  you can do it like this   import   Observable   from  rxjs Observable   import   of   from  rxjs observable of   import   delay   from  rxjs operators    fakeObservable   of  dummy   pipe delay 5000      In RxJS 6   import   of   from  rxjs   import   delay   from  rxjs operators    fakeObservable   of  dummy   pipe delay 5000      If you want to delay each emitted value try  from  1  2  3   pipe concatMap item   gt  of item  pipe delay 1000

User · Answer

What you want is a timer      RxJS v6  import   timer   from  rxjs      emit  1  2  3  after 1 second  const source   timer 1000  map   1  2  3      output   1  2  3  const subscribe   source subscribe val   gt  console log val

User · Answer

import   as Rx from  rxjs Rx    We should add the above import to make the blow code to work  Let obs   Rx Observable      interval 1000  take 3    obs subscribe value   gt  console log  Subscriber      value

User · Answer

Using the following imports     import  Observable  from  rxjs Observable   import  rxjs add observable of   import  rxjs add operator delay     Try this     let fakeResponse    1 2 3   let delayedObservable   Observable of fakeResponse  delay 5000   delayedObservable subscribe data   gt  console log data      UPDATE  RXJS 6  The above solution doesn t really work anymore in newer versions of RXJS  and of angular for example     So the scenario is that I have an array of items to check with an API with  The API only accepts a single item  and I do not want to kill the API by sending all requests at once  So I need a timed release of items on the Observable stream with a small delay in between   Use the following imports     import   from  of   from  rxjs   import   delay   from  rxjs internal operators   import   concatMap   from  rxjs internal operators     Then use the following code     const myArray    1 2 3 4    from myArray  pipe          concatMap  item   gt  of item  pipe   delay  1000            subscribe   timedItem   gt            console log timedItem            It basically creates a new  delayed  Observable for every item in your array  There are probably many other ways of doing it  but this worked fine for me  and complies with the  new  RXJS format

[angular] How can I create an observable with a delay

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