Handle React Suspense Errors with an Error Boundary

Kent C. Dodds
InstructorKent C. Dodds

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Published 4 years ago
Updated 3 years ago

Error Boundaries are the way you handle errors with React, and Suspense embraces this completely. Let's take a look at how to handle asynchronous errors with Suspense and Error Boundaries.

Instructor: [0:00] As great as this is that we can get our Pokémon data, what if I had a mistype here and instead it was Pikacha? If I save that, we get a refresh and it's just going to hang out here forever. If I open up my developer tools and look in my console, I'm going to see that that request did fail because there's no Pokémon by the name of Pikacha.

[0:20] We need to handle our errors and display something useful to the user. What we're going to do here is, we have our success handler and then as a second argument, we'll have our error handler. With this, we need to assign that error to, I don't know, let's make a variable called Pokémon error. We'll assign that error here. Let's make that variable Pokémon error.

[0:42] Then in our Pokémon info, we'll say if there's a Pokémon error, then we can actually just throw the Pokémon error, and we can rely on an error boundary to catch that for us. It just so happens that we have a utils file here. This has an error boundary built out for us. This is the standard error boundary API that React has supported for quite some time.

[1:03] We're just going to import that from our utils. Let me just grab that. Then, we'll render our error boundary around our Suspense component. We'll say error boundary right here, and that error boundary is going to catch that thrown error. Here we have it. There was an error, and we have some additional information for our particular error.

[1:22] Let's go ahead and let's try one of these other Pokémon. We'll say Mew. Save that, get a refresh, and there's Mew's information. Again, if we give it a Pokémon that isn't supported, we're going to get that error boundary catching the error that we're throwing, so that we can handle that error appropriately.

[1:37] In review, to handle errors with Suspense, you're going to need to have some sort of tracking of the error that is happening. Then you can simply throw that error during render, and rely on the error boundary to catch that and display the information appropriately. Alternatively, we could have just rendered some JSX here, but I prefer to rely on error boundaries when handling errors in my app.

[1:58] The error boundary we're using is a pretty standard error boundary that React has supported for quite some time, which implements the getDerivedStateFromError static method to manage our error state. This is what's going to render out the message when we experience an error.

Viktor Soroka
Viktor Soroka
~ 4 years ago

When you said that you prefer relying on ErrorBoundary in the app, does it mean that you wrap individual components and thus have multiple instances of it?

Kent C. Dodds
Kent C. Doddsinstructor
~ 4 years ago

Think of Error Boundaries as try/catch blocks. It can be useful to have one that wraps the whole app, but then it's good to wrap it around specific places to give more helpful/contextual error messages.