10 Axios Best Practices

Axios is a promise-based HTTP client that works both in the browser and in the node.js environment. It provides a simple and clean API for making HTTP requests.

In this article, we will discuss 10 best practices for using Axios, including how to use it in conjunction with other libraries, how to handle errors, and how to perform HTTP requests.

1. Use async/await

When making HTTP requests, Axios returns a promise. This promise is not handled by the browser’s event loop, so if we make a request and then immediately try to log the response, the console will be empty.

Instead, we need to use async/await, which is a way of handling promises that makes our code look like it’s synchronous. With async/await, we can make a request and then immediately log the response.

2. Handle errors with catch()

When an error occurs in a JavaScript program, the default behavior is for the program to stop executing. This is known as a “runtime error.”

If you don’t handle errors, your program will crash and the user will see an error message. This is not ideal, especially if you’re building a user-facing application.

Instead, you should use catch() to handle errors gracefully. This way, you can display a friendly error message to the user and prevent your program from crashing.

Here’s an example of how to use catch() to handle errors:

“`
axios.get(‘/user’)
.then(response => {
// handle success
})
.catch(error => {
// handle error
})
.finally(() => {
// always executed
});
“`

As you can see, the catch() handler is attached to the promise chain after the then() handler. This ensures that the code inside catch() will only be executed if an error occurs.

The finally() handler is optional, but it’s generally a good idea to include it. This handler is executed regardless of whether or not an error occurs. It’s typically used for cleanup tasks, such as closing a loading spinner.

3. Use the spread operator to pass multiple headers

When you use the spread operator, it allows you to specify multiple headers at once. This is important because it means that you can specify different headers for different types of requests.

For example, you might want to set a header for all GET requests, but not for POST requests. Or you might want to set a header for all requests to a certain domain, but not for requests to other domains.

Thespread operator makes it easy to do this. All you have to do is specify the headers you want to set as an object, and then use the spread operator to pass them into the axios.request() method.

This is a much cleaner way to set headers than specifying each header individually. It also makes it easier to change or remove headers later on, if necessary.

4. Pass a config object as the second argument

The Axios config object allows you to specify the following:

– The HTTP method (GET, POST, PUT, etc.)
– The URL
– Data to be sent in the request body (for POST and PUT requests)
– Query parameters (for GET requests)
– HTTP headers

By specifying all of this information in the config object, you make it easier to understand what the request is doing, and you also make it easier to change the request if necessary. For example, if you need to change the URL, you can simply change it in the config object, rather than searching through the code for all instances of the URL.

5. Use axios.all() for concurrent requests

When making multiple requests, it’s important to note that they are all asynchronous. This means that they will not necessarily complete in the order in which they were made. In some cases, this may not matter. But in others, it might be important to know that request A completed before request B.

To ensure that requests complete in the order in which they were made, you can use axios.all(). This method takes an array of promises and returns a new promise that only resolves when all of the promises in the array have resolved.

This is useful for concurrent requests because it guarantees that they will all complete before the next code block is executed.

6. Cancel requests using axios.CancelToken

If you make a request and then navigate to another page before the response has returned, there’s a good chance that your request will still be processed even though you no longer need the data. This wastes resources on both the client and server, and can lead to unexpected results in your app.

To avoid this, you can use axios.CancelToken to cancel requests that are no longer needed. When a request is cancelled, Axios will automatically abort the request and reject the promise with a Cancel error.

This is an important best practice to keep in mind when using Axios, and will help you build more efficient and reliable applications.

7. Create an instance of Axios and use it in your app

When you create an instance of Axios, you can specify certain options that will be used for all requests made from that instance. This includes things like the base URL, headers, and other options.

Creating an instance also allows you to intercept requests and responses so you can add your own logic before or after they are handled by Axios. This is useful for things like adding authentication headers or logging information about each request.

Finally, using an instance of Axios means you can easily switch between different environments (like development, staging, and production) without having to change any code.

8. Set default values for all future requests

If you make a request to a server, and the server responds with an error, Axios will automatically reject the promise. This is by design, and it’s actually quite useful, because it means you don’t have to check for errors in every single request.

However, there are times when you might want to handle errors differently. For example, you might want to show an error message to the user, or you might want to log the error to a file.

To do this, you need to set a default error handler, using axios.defaults.onError. This function will be called whenever there is an error in any Axios request.

The onError function takes two arguments: the first is the error object, and the second is the axios config object. This gives you access to everything that was in the original request, including the URL, method, data, and headers.

With this information, you can decide how to handle the error, and whether to reject the promise or not.

9. Intercept request or response data before they are handled by then or catch

If you’re making a request to an API endpoint that doesn’t exist, or you’re getting a 500 error from the server, then chances are that your then function will never be called. This is because the promise will be rejected before it ever gets to the then function.

However, if you intercept the request or response data with an Axios interceptor, then you can still handle the error in the catch function.

Interceptors are also useful for logging, setting headers, and other common tasks that need to be done for every request or response.

10. Transform request or response data before they are sent or received

Transforming data is important for several reasons. For one, it can help ensure that data is in the proper format for the receiving party. Additionally, transforming data can help reduce payload size, which can be important when working with mobile devices or other constrained environments.

Axios provides a number of ways to transform data. One way is to use the Axios TransformRequest and TransformResponse functions. These functions take two arguments: the data to be transformed, and an array oftransformers. Each transformer is a function that takes the data as input and returns the transformed data.

For example, suppose you have an API that expects all dates to be in ISO 8601 format. You could use the following transformer to ensure that all dates are properly formatted before they are sent to the API:

function dateTransformer(data) {
return data.map(function(item) {
if (item.date) {
item.date = moment(item.date).format(‘YYYY-MM-DD’);
}
return item;
});
}

Alternatively, suppose you have an API that returns all dates in Unix timestamp format. You could use the following transformer to convert those timestamps into JavaScript Date objects:

function dateTransformer(data) {
return data.map(function(item) {
if (item.date) {
item.date = new Date(item.date * 1000);
}
return item;
});
}