How create a list directory with node filesystem

Unlocking the Power of File Operations in Node.js: Exploring a Practical Example

In the world of programming, managing files and directories is a fundamental task. Whether you're organizing data or dealing with user-uploaded files, having a grasp of file operations is crucial. In this article, we'll dive into a practical example of file and directory manipulation using Node.js. We'll explore a piece of code that demonstrates how to list directory contents, save them to a JSON file, and store them in memory.

Introduction to the Code

Let's take a look at the code snippet provided:

const fs = require('fs')

function listDirectory(path) {
  try {
    return fs.readdirSync(path)
  } catch (error) {
    return error.message
  }
}

function saveToJson(data, filename) {
  try {
    fs.writeFileSync(filename, JSON.stringify(data, null, 4))
    return true
  } catch (error) {
    return error.message
  }
}

function main() {
  const directoryPath = '/home/emmanuel/Desktop/Curso-JS-Moderno' // Replace with a directory path in your case
  const contents = listDirectory(directoryPath)

  if (Array.isArray(contents)) {
    console.log('Directory Contents:', contents)

    // Option 1: Save to a JSON file
    const jsonFilename = 'directory_contents.json'
    if (saveToJson(contents, jsonFilename)) {
      console.log(`Contents saved to '${jsonFilename}'`)
    } else {
      console.log('Error saving to JSON.')
    }

    // Option 2: Store in an in-memory array
    const inMemoryArray = contents
    console.log('Contents in memory:', inMemoryArray)
  } else {
    console.log('Error:', contents)
  }
}

main()

Code Breakdown

Let's break down the code step by step:

1. Importing the fs Module: The code starts by importing the Node.js fs module, which provides file system-related functionality.

2. listDirectory Function: This function takes a path as its parameter, representing the directory path you want to list the contents of. It uses fs.readdirSync(path) to synchronously read the contents of the directory. If successful, it returns an array of directory entries. If an error occurs, it returns an error message.

3. saveToJson Function: This function takes data (the content to be saved) and a filename as parameters. It attempts to write the provided data to the specified file in JSON format using fs.writeFileSync(filename, JSON.stringify(data, null, 4)). The null and 4 arguments in JSON.stringify add formatting for readability. If successful, it returns true; otherwise, it returns an error message.

4. main Function: This is the main entry point of the script. It defines the directoryPath variable, which should be replaced with the actual path of the directory you want to work with. It then calls the listDirectory function to retrieve the contents of the directory.

5. Processing Contents: If the returned contents is an array (indicating successful retrieval), the script proceeds to process the data.

   • It first logs the directory contents to the console.
   • It then demonstrates two options for handling the contents:
     • Option 1: Saving the contents to a JSON file with a specified filename.
     • Option 2: Storing the contents in an in-memory array.

6. Handling Errors: If the returned contents is not an array (indicating an error occurred during retrieval), an error message is logged to the console.

Conclusion

In this article, we've explored a practical example of file and directory manipulation using Node.js. The provided code showcases how to list the contents of a directory, save them to a JSON file, and store them in an in-memory array. This knowledge can be applied to a wide range of scenarios, such as organizing data, creating backups, or facilitating user interactions involving files. Armed with this understanding, you're well-equipped to tackle file operations effectively in your Node.js projects.