Node.js: read a text file into an array. (Each line an item in the array.)

A method for every file size

When working with Node.js, the size of the file you're aiming to process plays a critical role in deciding the method to use. The fs.readFileSync function is your best bet for smaller files. It's quick and easy to use but could leave you twiddling your thumbs waiting for larger files to finish processing.

Here's how you can handle larger files using the fs.readFile function:

// fs.readFile comes to the rescue for larger files
fs.readFile('largeFile.txt', (err, data) => {
  if (err) throw err; // Hey, it's no "err"or to fall. But, it is to not catch yourself.
  const lines = data.toString().split('\n');
  // Now the ball is in your court to process the lines array.
});
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For extremely large files, go with readable streams:

// Streams - for when your file is heavier than your last failed diet
const stream = fs.createReadStream('veryLargeFile.txt', 'utf8');

stream.on('data', (chunk) => {
  const lines = chunk.split('\n');
  // It's chunky salsa time! Go ahead, process the lines.
});

stream.on('end', () => {
  // end-of-file logic. Nah, it ain't the end of the world!
});
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Looking for a memory-efficient way? readline module saves the day:

const readline = require('readline');
const lineReader = readline.createInterface({
  input: fs.createReadStream('largeFile.txt'),
  crlfDelay: Infinity
});

lineReader.on('line', (line) => {
  // Batch processing at your service. Process each line right here, right now!
});
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Considerations for cross-platform line breaks

Line break variations can be a tough nut to crack while maintaining consistency across different operating systems. Ensure you handle these variations consistently to avoid any hiccups in accurate array splitting:

const EOL = require('os').EOL;
const lines = fs.readFileSync('file.txt', 'utf8').split(EOL); // Split wisely. Remember, it's a "line's" life at stake!
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Error-handling and memory management

Exception handling is like a watchdog for your code. For a modern approach, you can use the fs.promises API with async-await mechanism:

const fsPromises = require('fs').promises;

async function readFileToArray(filename) {
  try {
    const data = await fsPromises.readFile(filename, 'utf8');
    return data.split('\n');
  } catch (err) {
    console.error('Caught read-handed: Error reading the file', err);
  }
}
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And, keep a close eye on your memory usage. Reading large files have this knack to blow memory consumption out of proportion if not buffered correctly.

Performance boosters and Streaming perks

Getting your performance up a notch could means tweaking your logic a tad bit. Here are a few tips:

• Ditch split() for indexOf and substring when parsing streams. The lesser the intermediary arrays, the smoother the processing.
• Only once you've identified the bounds of a line, convert the buffer to string.
• Tame your streams to be cognizant of the file's encoding. Doing so saves you from a buffer-to-string conversion with every chunk.

Keeping up the code compatibility

Fostering resilience and ensuring compatibility means:

• Making your code compatible with Node.js version 10.0.0 and later.
• Keeping an eye out for edge cases such as unexpected characters.
• Tailoring the code to work seamlessly across platforms using process.platform or os.EOL.