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: