Global namespace example

closure.js

(function() {
  global_var = "This is a globally scoped variable";
  console.log(global_var);
  
  return {
    data: "example"
  }
})()

console.log(global_var);

global.js

function global_vars() {
  global_var = "This is a globally scoped variable";
  console.log(global_var);
}

global_vars();

// the variable "local" exists in the global namespace
// because it was created without the `var` keyword
console.log(global_var);

local.js

function local_vars() {
  var local = "This is scoped to this function only";
  console.log(local);
}

local_vars();

// The variable "local" is undefined because we are in the global scope
console.log(typeof local === 'undefined')