example.coffee

x = 1
foo = ->
  x = 2
  return

foo()

example.js

var x=1; 

var foo = function (){
  var x=2; return;
}; 

foo(); 

example_fix.coffee

x = 1
foo = ->
  @x = 2 
       
foo()
console.log x;

gistfile1.txt

npm install -g coffee-script

coffee -c ./example.coffee


### compiled file 

// Generated by CoffeeScript 1.6.3
(function() {
  var foo, x;

  x = 1;

  foo = function() {
    return x = 2;
  };

  foo();

  console.log(x);

}).call(this);