global.js

//global variable 
test = 'hello';

//is exactly the same as
global.test = 'hello';

//local variable - this will definitly override your global variable
var test = 'world';

//using the process scope, if, and really if, you can't do without a global variable
process.test = 'world';

//Now both will be defined and using `process` will avoid any confusion
console.log(test + process.test);
//hello world