gzip without header and base 64 encode, in Node

gunzipbase64.js

var fs = require('fs');
var zlib = require('zlib');

// Read local subtitle, gunzip it, encode to base64
var toUpload;                                     // future gunzipped/base64 encoded string
var path = 'foo/bar.srt';                         // path to subtitle
fs.readFile(path, function(err, data) {           // read subtitle
  if (err) throw err;                             // handle reading file error
  zlib.deflate(data, function(err, buffer) {      // gunzip it
    if (err) throw err;                           // handle compression error
    toUpload = buffer.toString('base64');         // encode to base64
  });
});

// Decode base64 string, decompress content, write in file
var data = 'xxx';                                 // base64 encoded string recieved from OpenSubtitles
var path = 'foo/bar.srt';                         // path to future subtitle file
var buf = new Buffer(data, 'base64');             // read the base64 string
zlib.unzip(buf, function (err, buffer) {          // decompress the content
  if (err) throw err;                             // handle decompression error
  var content = buffer.toString('utf8');          // encode in utf-8
  fs.writeFile(path, content, function (err) {    // write file to path
    if (err) throw err;                           // handle writing to file error
  });
});

Some extra reading:

• zlib: https://nodejs.org/api/zlib.html
• fs: https://nodejs.org/api/fs.html
• Buffers (toString() & new Buffer()): https://nodejs.org/api/buffer.html