index.js

var fs    = require('fs')
  , Iconv = require('iconv').Iconv
  , iconv = new Iconv('UTF-8', 'UTF-16')
  , exec  = require('child_process').exec
  , spawn = require('child_process').spawn
  , temp  = require('temp');

exports.generateFdf = function(data, fileName) {
  var header, body, footer, dataKeys;

  header = Buffer([]);
  header = Buffer.concat([ header, new Buffer("%FDF-1.2\n") ]);
  header = Buffer.concat([ header, new Buffer((String.fromCharCode(226)) + (String.fromCharCode(227)) + (String.fromCharCode(207)) + (String.fromCharCode(211)) + "\n") ]);
  header = Buffer.concat([ header, new Buffer("1 0 obj \n") ]);
  header = Buffer.concat([ header, new Buffer("<<\n") ]);
  header = Buffer.concat([ header, new Buffer("/FDF \n") ]);
  header = Buffer.concat([ header, new Buffer("<<\n") ]);
  header = Buffer.concat([ header, new Buffer("/Fields [\n") ]);

  footer = Buffer([]);
  footer = Buffer.concat([ footer, new Buffer("]\n") ]);
  footer = Buffer.concat([ footer, new Buffer(">>\n") ]);
  footer = Buffer.concat([ footer, new Buffer(">>\n") ]);
  footer = Buffer.concat([ footer, new Buffer("endobj \n") ]);
  footer = Buffer.concat([ footer, new Buffer("trailer\n") ]);
  footer = Buffer.concat([ footer, new Buffer("\n") ]);
  footer = Buffer.concat([ footer, new Buffer("<<\n") ]);
  footer = Buffer.concat([ footer, new Buffer("/Root 1 0 R\n") ]);
  footer = Buffer.concat([ footer, new Buffer(">>\n") ]);
  footer = Buffer.concat([ footer, new Buffer("%%EOF\n") ]);

  dataKeys = Object.keys(data);

  body = new Buffer([]);

  for(var i=0; i<dataKeys.length; i++) {
    var name = dataKeys[i];
    var value = data[name].toString().replace("\r\n","\r");

    body = Buffer.concat([ body, new Buffer("<<\n") ]);
    body = Buffer.concat([ body, new Buffer("/T (") ]);
    body = Buffer.concat([ body, iconv.convert(name.toString()) ]);
    body = Buffer.concat([ body, new Buffer(")\n") ]);
    body = Buffer.concat([ body, new Buffer("/V (") ]);
    body = Buffer.concat([ body, iconv.convert(value.toString()) ]);
    body = Buffer.concat([ body, new Buffer(")\n") ]);
    body = Buffer.concat([ body, new Buffer(">>\n") ]);
  }

  var fdf =  Buffer.concat([ header, body, footer ]);
  return fdf;
}

exports.generatePdf = function(data, templatePath,callback) {
  var tempName = temp.path({suffix: '.pdf'});
  var tempNameResult = temp.path({suffix: '.pdf'});

  child = spawn("pdftk", [templatePath,"fill_form","-","output",tempName,"flatten"]);

  child.on('exit', function(code) {
    var cmd = "gs -dNOCACHE -sDEVICE=pdfwrite -sOutputFile="+tempNameResult +" -dbatch -dNOPAUSE -dQUIET  " + tempName +"  -c quit"
    console.log(cmd);
    exec(cmd,  function (error, stdout, stderr) {
      console.log('stderr: ' + stderr);
      if (error !== null) {
        console.log('exec error: ' + error);
      }
      result = fs.readFileSync(tempNameResult)

      // Delete files
      try {
        fs.unlinkSync(tempName);
        fs.unlinkSync(tempNameResult);
      } catch (e) {
        console.log("Cannot delete temporary files - not found");
      }
      callback(result);
     });
   });

  child.stdin.write(exports.generateFdf(data));
  child.stdin.end();
  child.on('error', function (err) {
    console.log('Errror', err);
  });
  child.stderr.on('data', function (data) {
    console.log('stderr: ' + data);
  });

}