Scope, hoisting, event loop: Global scope

Scope is the set of variables that’s visible to a part of the program.

In JavaScript we have a 3 different scopes:

  • global scope
  • function scope
  • block scope

In JavaScript, everything that’s not defined inside a function or block is attached to the global object.

Take this example:

var age = 20

We define an age variable.

We can always reference this variable inside any other function or loop or anywhere, using age.

const age = 20
console.log(age) //20
let age = 20
console.log(age) //20

Lessons in this unit:

0: Introduction
1: ▶︎ Global scope
2: Function scope
3: Block scope
4: Shadowing
5: Hoisting
6: Closures
7: An issue with `var` variables and loops
8: The event loop