Variable Scopes in JavaScript

In programming, the scope of a variable refers to the area of the code where a variable can be accessed and used.

In JavaScript, there are three main types of variable scope: global, local, and block.

Global variables

Global variables are variables that are accessible and modifiable from anywhere in the script, including within control statements and functions.

They are usually declared and initialized at the top of the script, and are used to store values that need to be shared across functions or for data that needs to maintain its state (or value) throughout the entire script execution, referred to as constants.

Example

Let's consider this script, that implements two functions named incrementCounter and resetCounter used to change the value of the global counter variable:

let counter = 0;function incrementCounter() {  counter = counter + 1;}function resetCounter() {  counter = 0;}incrementCounter();