How to use fs promises in Node.js

// Import fs promises
import { readFile, writeFile, readdir, mkdir, stat, access } from 'fs/promises'
import { constants } from 'fs'

// Read file with promises
async function readFileExample() {
  try {
    const data = await readFile('config.json', 'utf8')
    const config = JSON.parse(data)
    console.log('Config loaded:', config)
    return config
  } catch (error) {
    console.error('Error reading file:', error.message)
    return null
  }
}

// Write file with promises
async function writeFileExample(data) {
  try {
    const jsonData = JSON.stringify(data, null, 2)
    await writeFile('output.json', jsonData, 'utf8')
    console.log('File written successfully')
  } catch (error) {
    console.error('Error writing file:', error.message)
  }
}

// Multiple file operations
async function processFiles() {
  try {
    // Check if directory exists
    await access('./data', constants.F_OK)

    // Read directory contents
    const files = await readdir('./data')
    console.log('Files found:', files)

    // Process each file
    const results = []
    for (const file of files) {
      if (file.endsWith('.json')) {
        const content = await readFile(`./data/${file}`, 'utf8')
        const data = JSON.parse(content)
        results.push({ file, data })
      }
    }

    // Write combined results
    await writeFile('combined.json', JSON.stringify(results, null, 2))
    console.log('Processing complete')

  } catch (error) {
    if (error.code === 'ENOENT') {
      console.log('Data directory does not exist, creating...')
      await mkdir('./data', { recursive: true })
    } else {
      console.error('Error processing files:', error.message)
    }
  }
}

// File system utilities with promises
async function fileSystemUtils() {
  try {
    // Get file stats
    const stats = await stat('package.json')
    console.log('File size:', stats.size)
    console.log('Is file:', stats.isFile())
    console.log('Modified:', stats.mtime)

    // Check file accessibility
    await access('package.json', constants.R_OK | constants.W_OK)
    console.log('File is readable and writable')

    // Create nested directories
    await mkdir('./src/components/ui', { recursive: true })
    console.log('Nested directories created')

  } catch (error) {
    console.error('File system operation failed:', error.message)
  }
}

// Parallel file operations
async function parallelOperations() {
  try {
    const [file1, file2, file3] = await Promise.all([
      readFile('file1.txt', 'utf8'),
      readFile('file2.txt', 'utf8'),
      readFile('file3.txt', 'utf8')
    ])

    console.log('All files read successfully')
    return { file1, file2, file3 }

  } catch (error) {
    console.error('Error reading files in parallel:', error.message)
  }
}