Extend Your Reactive Logic in RxJS using Observable-like Proxies that Delay or Drop Events

InstructorRares Matei

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Our app is working! But now our manager comes in and tells us that some tasks in our app are finishing very fast, so users are seeing a short glimpse of the spooner which makes the app look glitchy. Our new requirement is to wait at least 2 seconds before showing the spinner. So without introducing any complexity into our main observable, we will create a new intermediary stream that will be a proxy between the observable that immediately tells us when to show the spinner and the one that actual shows it. This new proxy will delay the events accordingly.

Colin Principe
~ 4 years ago

In order to get this to work in my environment I had to change the import from rxjs/operators to rxjs and put spinnerDeactivated and flashThreshold into an array:

https://jsfiddle.net/Lcxgntwb/

Environment: OSX, Webstorm 2020.1.1, Firefox 75 64-bit.

Colin Principe
~ 4 years ago

Sorry, by "this" I mean the spinner show time on the Almost Quick Task.

Rares Mateiinstructor
~ 4 years ago

Hi Colin! I think you your comment is for the next lesson - 12.

And you are correct, we need to import "combineLatest" from the top-level "rxjs" package. If you look in the GitHub, that's how we did it: https://github.com/rarmatei/egghead-thinking-reactively/blob/lesson10/src/lesson-code/TaskProgressService.js

And combineLatest accepts a variable number of observables as input (not an array), so I'm surprised it's not working for you:

  • what version of rxjs are you using?
  • can you clone my repository, run npm install and let me know if it's still not working for you?