eolas/zk/Global_object_in_NodeJS.md

---
tags:
  - node-js
---

# Global object

> In Node every function and variable should be scoped to a module. We should
> not define functions and variables within the global scope.

- In Node the equivalent to the browser's `Window` object is `global`. The
  properties and methods that belong to this method are available anywhere in a
  program.

- Just as we can technically write `Window.console.log()`, we can write
  `global.console.log()` however in both cases it is more sane to use the
  shorthand.

- However if we declare a variable in this scope in browser-based JavaScript,
  this variable becomes accessible via the `Window` object and thus is
  accessible in global scope. The same is not true for Node. If you declare a
  variable at this level it will return undefined.

- This is because of Node's modular nature. If you were to define a function
  `foo` in a module and then also define it in the global scope, when you call
  `foo`, the Node interpreter would not know which function to call. Hence it
  chooses not to recognise the global `foo`, returning undefined.