How to Fetch and Decompress .gz Files with Axios in JavaScript

Описание: Learn how to use Axios to handle `.gz` files in JavaScript by fetching and decompressing them for easy access to the underlying data.
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This video is based on the question https://stackoverflow.com/q/60495059/ asked by the user 'Jat90' ( https://stackoverflow.com/u/10213512/ ) and on the answer https://stackoverflow.com/a/63858933/ provided by the user 'Ario' ( https://stackoverflow.com/u/1379914/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fetching and Decompressing .gz Files with Axios in JavaScript

When working with HTTP requests in JavaScript, it isn't uncommon to encounter compressed files such as those with a .gz extension. A common issue arises when developers try to fetch these files using libraries like Axios and end up with gibberish data instead of the expected raw information. In this guide, we will specifically discuss how to properly fetch an .xml.gz file using Axios and decompress it to retrieve the underlying XML data.

The Problem: Retrieving Raw Data from .gz Files

You might have attempted to fetch a .gz file using Axios with the following code snippet:

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This can lead to surprising results. Instead of the expected content, you may see strange characters and sequences like this:

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What this means is that the response is in a compressed format, and without decompressing it, you won't be able to read the underlying data.

The Solution: Using Axios and Zlib

To handle .gz files correctly, you need to make a couple of adjustments in your code. Here’s a structured breakdown of how to achieve this:

Step 1: Set the Response Type

The first modification involves changing the responseType of your Axios request. By default, Axios expects to handle textual data, but we need to specify that we are expecting an arraybuffer, which is suitable for binary data like the compressed file.

Step 2: Use Zlib for Decompression

After successfully fetching the .gz file, the next step is to decompress it. For this, we can use Node.js's built-in zlib module, which provides methods for compressing and decompressing files.

Here is how you can implement both steps in a single code snippet:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Importing Modules: We begin by importing the required axios and zlib modules.

Setting Up the URL: Define the URL where the .gz file is located.

Defining the Async Function: We create an asynchronous function named test() to fetch and decompress the data.

Fetching Data: The axios.get call is made with the responseType set to arraybuffer to handle binary data correctly.

Decompressing: Once the data is fetched, zlib.gunzip is used to decompress it. If successful, the raw XML data will be logged to the console.

Error Handling: Basic error handling is implemented to catch and log any problems during the fetch or decompression process.

Conclusion

By following the steps outlined above, you can easily fetch and decompress .gz files using Axios in a JavaScript environment. This allows you to access the raw data contained within these compressed files without any hassle. Happy coding!