Variables in Javascript are the containers for storing the values of specific types. Variables can store a single value and there are three keywords in Javascript to store variables - Let, Var, and Const. The code showing the declaration of variables in Javascript is mentioned below -

let message = "Hello World" console.log(message)
//Output - Hello World

The Variables can be understood by an example that in our kitchen, we have various food items such as pulses, sugar, tea, coffee, and so on. So, the food items are data values and the container are variables.

Scoping of Variables

Scoping refers to a particular region in the code where the assigned variable is accessible. It is simply the place where we can use our declared variable again.

However, there are two types of scopes - Local Scope and Global Scope. The Local space is where the variables are accessed to a particular block of code Whereas Global variables can be accessed from anywhere in the code.

In the case of Global Variable, the variables are like - This Global scope can be understood by the example, for instance, If I am the owner of the website, I can access every piece of information whether it is data, content, etc. I will have no restrictions.

On the other hand, the visitor who comes to the website will have access to the information available publicly on the website and not of the backend.

Let, Var, and Const

All three keywords Let, Var, and const are used for declaring the variables. But a question arrives if all have the same working why not use only one?
So, the answer to this question is that the let keyword cannot be re-declared but can be updated, and also let is blocked scoped.

var keyword is globally scoped, can be re-declared, and updated within the scope.

Const Keyword is the most used keyword because the value initialized and declared with const cannot be changed throughout the code and is kept constant.

Variable Naming

There are certain limitations in giving names to the variables in Javascript which are mentioned below -

• The name of the variable must contain letters, digits, symbols, $, and _.
• The name of the variable must not start with a digit.
  
• The camel case conventions or Pascal conventions are commonly used in variable naming.