index.js

global.hi = "Hello";
goodbye = "See ya";

global = Object.freeze(global);

console.error('global.hi: %s', hi);
console.error('global.goodbye: %s', goodbye);

hi = "Nice to see you";
console.error('global.hi overridden? %s', hi === "Nice to see you");

try {
  x = "oops i leaked a global variable";
} catch (err) {
  //console.error(err.stack);
}
console.error('successfully leaked a variable?: %s', 'undefined' !== typeof x);

console.error('lets require some shiz');

require('./module');

module.js

try {
y = "leaked";
} catch (err) {}

console.error('leaked a global in a module? %s', 'undefined' !== typeof y);

hi = "howdy";

console.error('can override a global within in module? %s', hi === 'howdy');

Dropping window = Object.freeze(window); in our intranet! Thanks! :-)