Introduction to readdirp

readdirp is a Node.js package that provides a recursive version of fs.readdir, offering a powerful and flexible API for reading directories and their contents. This library is extremely useful for tasks such as searching for specific types of files, processing files, and maintaining directories. In this guide, we will explore some of the most useful APIs provided by readdirp, along with practical examples to help you understand how to leverage them effectively.

Installation

First, make sure to install readdirp using npm:

  npm install readdirp

Basic Usage

Here’s a simple example to get you started with readdirp:

  
    const readdirp = require('readdirp');

    readdirp('path/to/directory', { fileFilter: '*.js' })
      .on('data', (entry) => {
        console.log(entry.path);
      })
      .on('end', () => {
        console.log('All done!');
      });
  

Advanced Filtering Options

The readdirp() function allows you to filter files and directories based on specific criteria. You can filter by file extensions, directory names, and even by custom filter functions.

  
    const readdirp = require('readdirp');

    const settings = {
      fileFilter: ['*.js', '*.json'],
      directoryFilter: ['!node_modules']
    };

    readdirp('path/to/directory', settings)
      .on('data', (entry) => {
        console.log(entry.path);
      })
      .on('end', () => {
        console.log('Reading complete.');
      });
  

Using Stream API

readdirp supports Node.js streams, which means you can use it with pipes to process files efficiently:

  
    const readdirp = require('readdirp');

    readdirp('path/to/directory')
      .on('data', (entry) => {
        console.log(entry.path);
      })
      .pipe(process.stdout);
  

Asynchronous Iteration

With asynchronous iteration, you can use for await...of to iterate over file entries asynchronously:

  
    const readdirp = require('readdirp');

    async function listFiles() {
      for await (const entry of readdirp('path/to/directory')) {
        console.log(entry.path);
      }
    }

    listFiles().then(() => console.log('All files listed.'));
  

Full Application Example

Here is a complete application example that demonstrates the usage of the APIs mentioned above:

  
    const readdirp = require('readdirp');
    const fs = require('fs');

    async function processFiles() {
      const settings = {
        fileFilter: '*.txt',
        directoryFilter: ['!archive']
      };

      for await (const entry of readdirp('path/to/directory', settings)) {
        const data = fs.readFileSync(entry.fullPath, 'utf8');
        // Process the file content
        console.log(`Processing file: ${entry.path}`);
        console.log(data);
      }
    }

    processFiles().then(() => console.log('All files processed.'));
  

Conclusion

readdirp is a versatile and powerful tool for Node.js developers, simplifying the process of reading directory contents and enabling advanced file operations with ease. Whether you’re performing basic directory reading tasks or complex file processing operations, readdirp offers a range of functionalities to meet your needs.

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