How To Catch 401 Error Using Fetch Method Of Javascript

The 401 error, also known as the Unauthorized error, is a common HTTP status code you might encounter while working with web APIs. It typically means you need proper authentication to access a resource, but fear not! In this guide, we'll walk you through how to catch a 401 error when using the fetch method in JavaScript.

First things first, let's set the stage. The fetch method is a modern API for making HTTP requests in JavaScript. It's commonly used to fetch data from a server or send data to a server in front-end applications. However, when dealing with APIs that require authentication, handling errors like the 401 error becomes crucial.

To catch a 401 error when using the fetch method, you can check the response status in the promise chain. Here's a simple example to illustrate this:

Javascript

fetch('https://api.example.com/data', {
  headers: {
    'Authorization': 'Bearer your_access_token'
  }
})
.then(response =&gt; {
  if (!response.ok) {
    if (response.status === 401) {
      throw new Error('Unauthorized: Please check your credentials');
    } else {
      throw new Error('An error occurred while fetching the data');
    }
  }
  return response.json();
})
.then(data =&gt; {
  console.log(data);
})
.catch(error =&gt; {
  console.error(error.message);
});

In the above code snippet, we make a fetch request to 'https://api.example.com/data' with the necessary authorization header. Upon receiving the response, we first check if it's ok (i.e., the status is in the range 200-299). If not, we specifically handle the case where the status is 401 by throwing a custom error message.

By catching the 401 error explicitly, you can provide better feedback to the user or take appropriate actions in your application, such as prompting the user to reauthenticate or redirecting them to a login page.

It's worth noting that handling errors gracefully is an essential aspect of building robust web applications. By understanding how to catch specific errors like the 401 error, you can enhance the overall user experience and troubleshoot issues effectively.

In conclusion, catching a 401 error when using the fetch method in JavaScript involves checking the response status in the promise chain and handling it accordingly. Remember to test your error-handling logic thoroughly to ensure your application behaves as expected in various scenarios.

Keep practicing, stay curious, and happy coding!

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