useFetch: A Custom React Hook

One of the most common React Hooks that I’ve found myself using is one to handle API calls. Often we see ourselves writing almost the same codes in more than one different component. Ideally what we could do in such cases would be to extract that recurrent logic into a reusable piece of code (hook) and reuse it where the need be.

I am going to use Fetch API for the HTTP calls. You can use axios as well, it's up to you.

To convert this example to a custom hook, it would look like this:

This is a very basic example that has many issues; not including handling errors, loading indicator, etc. It’s already quite a bit few lines of code and is not reusable.

Our component could then call it like this:

Let's start to add the features I mentioned above.

The loading indicator is a must in my opinion. Because knowing the fetch process still goes on, we can show a loading component or an icon or something else for a nice user experience.

Let's define a state for loading to achieve that.

Our component could use it like this:

Here is another must feature for our custom hook. We’ll define 2 states, one is a boolean value that indicates whether has an error or not and another one is a string value that includes the error message.

We’ll be also using the try/catch syntax to set and handle error boundaries. It would look like this:

Our component could use it like this:

What if we would like to use this hook some after the component renders rather than the didMount stage? To achieve this, we can use a prop (let's say: skip) to skip the data fetching function.

Our component could use it like this:

What if we would like to change the url dynamically to trigger the fetching process again? Why not? Let's implement it.

We’ll change the url prop name to initialUrl to use it as a state. The initialUrl prop will be the default value of the url state.

We’ll add url state to the dependency of the useEffect hook to trigger it again. Then we’ll export its setState function which is updateUrl to use it from our component.

Our component could use it like this:

What about parameters? And what about changing it dynamically to use it like filtering or something else? Sounds great. Let's implement this too.

We’ll take parameters as a prop which will be an object. And then, we’ll transpile them with encodeURIComponent to use properly. Following that, we’ll add params state to the dependency of the useEffect hook to trigger it again. It would look like this:

Our component could use it like this:

Another common thing I’ve needed is the ability to manually trigger the API call again. A good example would be a page with a list of resources and wanting to refresh the list from a callback after creating a new resource.

To do this we’ll simply keep a number in the state that’s dependent on the useEffect, that we increment every time we want to force a refresh.

Finally, it would look like this:

It could be then used in a way similar to this:

Have you noticed that we're setting isLoading state in response.ok, its else and catch cases? Let's use finally syntax for better development. It'll look like this:

In this post, I have explained and made a small demo to show how we can declaratively fetch data and render it on screen by using the useFetch hook with the native Fetch API.