Which RxJS operators necessitate unsubscription?

It can be confusing to know which operators in RxJS must be unsubscribed from to prevent subscription leaks. Some, like forkJoin, complete automatically, while others, such as combineLatest, never complete. Is there a comprehensive list or guideline available to determine which operators require manual unsubscription? The documentation doesn't seem to provide clear guidance.

As a relative newcomer to RxJS, I may be misunderstanding some concepts. Please correct me if needed.

For clarity, I am aware of using | async, but it's not feasible for my current project. I'm also utilizing takeUntil instead of direct unsubscribe calls. My query is specifically about identifying when to use takeUntil/unsubscribe after employing RxJS operators.

javascripttypescriptrxjs

Answer №1

forkJoin won't close automatically. Its completion depends on the observables it's working with. If those observables don't complete, neither will the one returned by forkJoin(). Similarly, combineLatest behaves in a comparable manner.

Generally speaking, all RxJS operators generate observables that terminate when the original observable(s) do - or at least when one of them does.

From a practical standpoint, this means that it is up to the developer utilizing RxJS to grasp the behavior of the observables they're feeding into an operator. Could the stream potentially remain open indefinitely? In such cases, it may be necessary to make adjustments so that it closes after a certain period of inactivity, like 5 seconds.

The key point here is that operators will either honor the completion of the input observable, or they will alter it (potentially completing it early) as intended. Common examples of the latter category include the "takes": take, takeWhile, takeUntil.

Dedicate enough time to engage with the library - study the documentation for each operator, experiment with them in your code, and don't hesitate to seek clarification if something seems unclear. Through this process, you'll become quite adept at distinguishing between different types of operators.

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