index.js

var spawn = require('child_process').spawn;
var slang = require('slang');

function quote(val) {
  // escape and quote the value if it is a string and this isn't windows
  if (typeof val === 'string' && process.platform !== 'win32')
    val = '"' + val.replace(/(["\\$`])/g, '\\$1') + '"';

  return val;
}

function wkhtmltopdf(input, options, callback) {
  if (!options) {
    options = {};
  } else if (typeof options == 'function') {
    callback = options;
    options = {};
  }

  var output = options.output;
  delete options.output;

  // make sure the special keys are last
  var extraKeys = [];
  var keys = Object.keys(options).filter(function(key) {
    if (key === 'toc' || key === 'cover' || key === 'page') {
      extraKeys.push(key);
      return false;
    }

    return true;
  }).concat(extraKeys);

  var args = [wkhtmltopdf.command, '--quiet'];
  keys.forEach(function(key) {
    var val = options[key];
    if (key !== 'toc' && key !== 'cover' && key !== 'page')
      key = key.length === 1 ? '-' + key : '--' + slang.dasherize(key);

    if (val !== false && !Array.isArray(val) && !(val instanceof  Object))
      args.push(key);

   //TODO: merge in changes from here: https://github.com/terradatum/node-wkhtmltopdf
    if (Array.isArray(val)) {
      val.forEach(function(v) {
        args.push(key);
        args.push(quote(v));
      });
    } else if (val instanceof Object) {
      Object.keys(val).forEach(function(k) {
        args.push(key);
        args.push(quote(k));
        args.push(quote(val[k]));
      });
    } else if (typeof val !== 'boolean') {
      args.push(quote(val));
    }
  });

  //ML - pass in files using the file:/// prefix
  var isUrl = /^(https?|file):\/\//.test(input);
  args.push(isUrl ? quote(input) : '-');    // stdin if HTML given directly
  args.push(output ? quote(output) : '-');  // stdout if no output file

  if (process.platform === 'win32') {
    var child = spawn(args[0], args.slice(1));
  } else {
    // this nasty business prevents piping problems on linux
    console.log(args.join(' '));
    var child = spawn('/bin/sh', ['-c', args.join(' ') + ' | cat']);
  }

  // call the callback with null error when the process exits successfully
  if (callback)
    child.on('close', function() { callback(null); });

  // setup error handling
  var stream = child.stdout;
  function handleError(err) {
    console.error(err);
    // if not, or there are listeners for errors, emit the error event
    if (!callback || stream.listeners('error').length > 0)
      stream.emit('error', err);
  }

  child.once('error', handleError);
  child.stderr.once('data', function(err) {
    handleError(new Error((err || '').toString().trim()));
  });

  //write input to stdin if it isn't a url
  if (!isUrl)
    child.stdin.end(input);

  //return stdout stream so we can pipe
  return stream;
}

wkhtmltopdf.command = 'xvfb-run --auto-servernum --server-args="-screen 0, 1024x768x24" wkhtmltopdf';
module.exports = wkhtmltopdf;