Скачать или смотреть How to Read and Open Two Different Files in Node.js?

Learn how to effectively read and open multiple files in Node.js without encountering errors. Discover the solutions that make file handling seamless.
---
This video is based on the question https://stackoverflow.com/q/64058399/ asked by the user 'Aquarius_Girl' ( https://stackoverflow.com/u/462608/ ) and on the answer https://stackoverflow.com/a/64063790/ provided by the user 'Manav Mandal' ( https://stackoverflow.com/u/7020219/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to read and open two different files in nodejs?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Read and Open Two Different Files in Node.js?

When working with Node.js, you might come across scenarios where you need to read and open multiple files. However, it's not uncommon to face errors like Error [ERR_STREAM_WRITE_AFTER_END]: write after end. In this guide, we will explore the nature of this problem and provide a clear, effective solution to handle multiple file operations gracefully.

Understanding the Problem

You might be attempting to read one file while simultaneously opening another, which can lead to issues if not handled correctly. The error you encountered indicates that your server is trying to write to a response stream after it has already been ended. This typically happens when you are not managing asynchronous operations correctly in Node.js.

Example Code and Error Explanation

In the code snippet below, we're trying to read z.html and mynewfile1.txt simultaneously:

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

The key issue here is that after argResult.end() is called for the first file, the server can no longer write to the response stream, leading to the mentioned error.

A Better Solution

To fix this, we can use Promises to handle the asynchronous nature of file operations better. By creating functions to read each file and using Promise.all(), we can ensure both files are read before completing the response. Here's how you can implement this:

Step 1: Define Reading Functions

We define two separate functions to handle reading each file. This encapsulates the logic and makes it manageable:

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

Step 2: Modify the Server Code to Use Promises

Now we will update the server code to use these functions. By using Promise.all(), we can make sure that we wait for both files to be read before ending the response:

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

Conclusion

By utilizing Promises and separating file read functionality into separate manageable components, we can avoid the common pitfalls associated with asynchronous operations in Node.js. This approach not only prevents the write after end error but also enhances the readability and maintainability of your code.

So, the next time you need to read multiple files in Node.js, remember this structured approach to handle files efficiently and without errors!