Question

I followed this example: Coffeescript and node.js confusion. require instantiates class?, but it doesn’t seem to work – the error is TypeError: undefined is not a function, so I must be doing something wrong. I have a simple coffee-script executable. Here are my steps:

Create a folder structure:

appmq

• my_executable

• my_class.coffee

• package.json

The file contents:

package.json:

{
    "name": "appmq",
    "version": "0.0.1",
    "description": "xxxxxx",
    "repository": "",
    "author": "Frank LoVecchio",
    "dependencies": {
    },
    "bin": {"appmq": "./my_executable"}
}

my_executable:

#!/usr/bin/env coffee
{CommandLineTools} = require './my_class'
cmdTools = new CommandLineTools()

cmdTools.debug()

my_class:

class CommandLineTools

  debug: () ->
    console.log('Version: ' + process.version)
    console.log('Platform: ' + process.platform)
    console.log('Architecture: ' + process.arch)
    console.log('NODE_PATH: ' + process.env.NODE_PATH)

module.exports = CommandLineTools

I then install the application via:

sudo npm install -g

Then I run the application (which produces the error I noted above):

appmq

Answer 1

Chris is right in his answer, but it’s got nothing to do with whether you have an explicit constructor in your class but rather what you are exporting.

If you want to export a single class like this:

module.exports = CommandLineTools

Then, when you require, what is returned will be what you assigned to module.exports above, i.e.:

CommandLineTools = require './my_class'

And this will work. What you are doing, is exporting in the manner described above, but you are using CoffeeScript’s destructuring assignment:

{CommandLineTools} = require './my_class'

which compiles to the js:

var CommandLineTools;
CommandLineTools = require('./my_class').CommandLineTools;

Which fails, because the require call will not return an object with the property CommandLineTools, but rather CommandLineTools itself. Now, if you wanted to use the destructuring assigment above, you would have to export CommandLineTools like this:

exports.CommandLineTools = CommandLineTools

I hope this will shed some light on the matter. Otherwise, ask away in the comments!