Hello guys ! 👋
Today, let's take a look at cancelling a web request with fetch and Abort Controller in React Hooks! 🤗
When we work with Fetch to manage data, we sometimes want to cancel the request (e.g. when we leave the current page, when we leave a modal, ...).
In the example below 👇, we fetch the data to display when switching route. But, we leave the route/page before the fetch is completed.
We just saw a memory leak in action! 💪🏼 Let’s see why this error occurred, and what it exactly means.
❓ WHY A MEMORY LEAK?: We have a component that performs an asynchronous
fetch(url) task, then updates the state of the component to display the elements, BUT we unmount the component before the request is even completed. The state of the unmounted component is updated (e.g.
setState), which follows a memory leak.
🚀 Let's use the new AbortController API !
Abort Controller allows you to subscribe to one or more Web Requests with the ability to cancel them. 🔥
Basics of AbortController
First of all, let's create a new AbortController object instance.
Now, we can access to
read-onlyproperty of the
AbortControllerinterface returns an AbortSignal object instance, which can be used to communicate with/abort a DOM request as desired." MDN Source
Let's see how to use it 💪
And finally, if we want to cancel the current request, just call
abort(). Also, you can get
controller.signal.aborted which is a
Boolean that indicates whether the request(s) the signal is communicating with is/are aborted (true) or not (false).
❗️ Note: When
abort()is called, the
fetch()promise rejects with a
Yeah, you just learned how to cancel a Web Request natively! 👏
🤩 Let's do this with React Hooks !
Below is an example of a component that retrieves data in order to display them:
If I leave the page too fast and the request is not finished: MEMORY LEAK
useEffect to subscribe to our
fetch request and to avoid memory leaks. We use the clean method of
useEffect for calling
abort() when our component unmount.
Now, no more memory leaks! 😍
As always, feel free to reach out to me! 😉
You can check this demo on abort-with-react-hooks.vercel.app.
Also, here the source code of this article in this gist.
Cheers 🍻 🍻 🍻
Top comments (21)
Damn this is a really cool article. I've run into that memory leak error before and now I understand what it is I'm looking at. Thank you for writing this!
A pleasure Tyler !!
Thanks for this well detailed article!!
I was facing the exact same issue, so I created this hook :
It basically works like React's useState, but it only updates the state if the component is mounted !
I thought it's an easy and elegant solution for that issue, what do you think ?
Yeah that's an idea ! I love that !! :)
What if i use redux? and use Axios rather than fetch?
It's the same approch for redux. And I think Axios provide a cancel function.
But I don't see a need for, never used Cancel kind of fun before also built some stuffs in React-Redux never saw console with such errors.......
I feel like your talking about dispatch........
+1. I am really new to React about 3-4 Months and would like to know in redux
This thing happens every time if you are using react hooks: reactjs.org/docs/hooks-intro.html
Thanks × 1000 👍.
This is one of the problem all people face when they are getting started with React. Thanks a lot for putting this out here so that it will help someone.
Thank you Gautam !
In the final example, why use
Because I use
fetchPostswhich is a dependency in my useEffect. But
fetchPostswill never updated (it's a
as dependency) so useEffect will not be executed a second time.
Right, I understand why it works, but why pick one over the other? Would it be faster to not wrap in useCalllback and use
? This is a fetch, so I guess any savings would be washed away in network.
I want to have a function for getting my data. Maybe in the future I would like to have a button to "refresh" my data. And call "fetchPosts" by clicking on it. Or maybe, for my future pagination by adding
pageas a new parameter of my function
Looks like it's flagged as experimental (not sure why) but still worth to mention compatibility table caniuse.com/#feat=abortcontroller around this feature.
Very nice article! Merci!