AbortController for cancellation in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of AbortController in Node.js?

AbortController is used to cancel asynchronous operations like fetch requests or timers before they complete.

beginner

How do you create an AbortController instance and use it to cancel a fetch request?

Create an AbortController instance, pass its signal to fetch, then call abort() on the controller to cancel.

beginner

What property of AbortController is passed to asynchronous functions to listen for cancellation?

The signal property is passed to async functions to detect when an abort is requested.

intermediate

What happens when abort() is called on an AbortController?

It triggers the signal to emit an abort event, causing operations listening to it to stop or throw an error.

intermediate

Can AbortController be reused after calling abort()?

No, once abort() is called, the controller cannot be reset or reused. You must create a new instance for new operations.

Which property of AbortController do you pass to a fetch request to enable cancellation?

A controller

B abort

C signal

D cancel

The signal property is passed to fetch to listen for cancellation.

What method do you call on an AbortController to cancel an operation?

A end()

B stop()

C cancel()

D abort()

abort() triggers cancellation.

After calling abort(), can you reuse the same AbortController instance for another operation?

A No, you must create a new instance

B Yes, but only after calling reset()

C Yes, it resets automatically

D No, but you can call abort() again

Once aborted, the controller cannot be reused; create a new one.

Which event does the signal emit when abort() is called?

A cancel

B abort

C stop

D end

The signal emits an abort event.

What is a common use case for AbortController in Node.js?

A To cancel long-running async tasks like fetch or timers

B To speed up synchronous code

C To handle errors in synchronous functions

D To create new HTTP servers

It is used to cancel asynchronous tasks before they finish.

Explain how you would use AbortController to cancel a fetch request in Node.js.

Think about the steps from creating the controller to stopping the fetch.

Describe what happens internally when abort() is called on an AbortController.

Focus on the signal and event behavior.