FTP Response Stream Parser

Common errors

• TypeError: ftp-response-parser is not a constructor

  cause Attempting to use an ESM `import` statement for a CommonJS-only module, which does not correctly resolve the constructor.
  fix Change your import statement to `const ResponseParser = require('ftp-response-parser');`.

• Error: read after end

  cause Invoking `parser.write()` on the stream after `parser.end()` has already been called, which signifies no more data will be written.
  fix Ensure all data is written to the parser using `parser.write()` before `parser.end()` is invoked. `parser.end()` should be the last write operation.

• Incomplete parsing of final FTP response lines (no specific error message)

  cause The readable stream's `read()` method is not being called sufficiently often in response to the `'readable'` event, or `parser.end()` was not called after all input data was provided.
  fix Ensure your `on('readable')` listener contains a `while` loop that continuously calls `parser.read()` until it returns `null`. Additionally, confirm `parser.end()` is called once all expected input has been written.

Warnings

• breaking This package is CommonJS-only and does not provide an ESM export. Direct `import` statements (e.g., `import { ResponseParser } from 'ftp-response-parser';`) will result in a runtime error.
  Fix: Use CommonJS `require()` syntax: `const ResponseParser = require('ftp-response-parser');` for module loading.
• gotcha The `ftp-response-parser` package is abandoned, with its last update occurring over a decade ago (May 2013). It may contain unaddressed bugs, security vulnerabilities, or compatibility issues with modern Node.js versions (e.g., Node.js v16+ and later).
  Fix: Evaluate alternatives if long-term support, security, or guaranteed compatibility with the latest Node.js runtime is required. Consider migrating to a more actively developed FTP client library or forking and maintaining this package if its core functionality is essential.
• gotcha As a Node.js `Stream`, if the input stream is not explicitly ended (via `parser.end()`) after all data has been written, the parser might hold onto buffered data indefinitely, potentially leading to memory leaks or incomplete parsing of the final response segments.
  Fix: Always call `parser.end()` when the entire input data has been fed to the parser to ensure all buffered data is processed and the stream is properly terminated, allowing the `end` event to fire.

Install

• npm install ftp-response-parser npm
• yarn add ftp-response-parser yarn
• pnpm add ftp-response-parser pnpm

Imports

• ResponseParser
  wrong:

  import { ResponseParser } from 'ftp-response-parser';

  correct:

  const ResponseParser = require('ftp-response-parser');

  This package is CommonJS-only, exporting the `ResponseParser` class directly as the module's default export. Named imports or ESM default imports are not supported.

Quickstart

Demonstrates how to instantiate the `ResponseParser`, listen for `readable` events to process parsed FTP response objects, handle potential errors, and feed it a multi-line FTP response string, ensuring the stream is properly terminated.

const ResponseParser = require('ftp-response-parser');
const myParser = new ResponseParser();

myParser.on('readable', function() {
  let line;
  while ((line = myParser.read()) !== null) {
    console.log(`Code: ${line.code}, Text: ${line.text}`);
  }
});

myParser.on('error', (err) => {
  console.error('Parser encountered an error:', err);
});

myParser.on('end', () => {
  console.log('End of FTP response stream.');
});

// Example FTP multi-line response string
const ftpResponse = `211-Features supported:\n EPRT\n EPSV\n MDTM\n MLST type*;perm*;size*;modify*;unique*;unix.mode;unix.uid;unix.gid;\n REST STREAM\n SIZE\n TVFS\n UTF8\n211 End FEAT.\n215 UNIX Type: L8\n331 Username ok, send password.\n230 Login successful.\n200 Type set to: Binary.\n250 "/test" is the current directory.\n`;

myParser.write(ftpResponse);
myParser.end(); // Signal that no more data will be written

console.log('Parser initialized and example data sent.');