Calling Node.js script from Rails app using ExecJS

Question

I have a Rails application that needs to run a node script. I imagine that using the ExecJS gem is the cleanest way to run JavaScript from a Rails app. However, so far, ExecJS has proved to be very frustrating to use.

Here is the script I need to run:

// Generated by CoffeeScript 1.7.1
(function() {
  var PDFDocument, doc, fs;
  fs = require("fs");
  PDFDocument = require('pdfkit');
  doc = new PDFDocument;
  doc.pipe(fs.createWriteStream('output.pdf'));
  doc.addPage().fontSize(25).text('Here is some vector graphics...', 100, 100);
  doc.save().moveTo(100, 150).lineTo(100, 250).lineTo(200, 250).fill("#FF3300");
  doc.scale(0.6).translate(470, -380).path('M 250,75 L 323,301 131,161 369,161 177,301 z').fill('red', 'even-odd').restore();
  doc.addPage().fillColor("blue").text('Here is a link!', 100, 100).underline(100, 100, 160, 27, {
    color: "#0000FF"
  }).link(100, 100, 160, 27, 'http://google.com/');
  doc.end();
}).call(this)

From my Rails console, I try this:

[2] pry(main)> file = File.open('test.js').read
[3] pry(main)> ExecJS.eval(file)
ExecJS::ProgramError: TypeError: undefined is not a function
from /Users/matt/.rvm/gems/ruby-2.1.0/gems/execjs-2.0.2/lib/execjs/external_runtime.rb:68:in `extract_result'

Note that I can run this script successfully using 'node test.js' and I am also able to run run the script using the backtick syntax Ruby offers:

`node test.js`

But that feels like a hack...

Answer 1

It's erroring out because require() is not supported by EvalJS. 'require' is undefined, and undefined is not a function. ;)