Javascript Variables

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Variables are blocks for storing data.
3 ways to declare variables

var
let
const

Declaring the javascript variable

Variable is declared when we create the variable. You can declare the javascript variable with let or var keyword.
var name;
or
let name;
After the declaration, the variable has no value it is undefined.
To assign a value to the variable, use the equal sign:
name = “awias butt”
Now it is a variable with type string.

Using var

The var is the oldest keyword to declare a variable in JavaScript. The scope of the var keyword is the global or function scope. It means variables defined outside the function can be accessed globally, and variables defined inside a particular function can be accessed within the function.
Example: Variable ‘number’ is declared globally. So, the scope of the variable ‘number’ is global, and it can be accessible everywhere in the program.
<script> Var number = 10; Function call(){ Console.log(number); } Call(); Console.log(number); </script>
Output
10
10

Using let

The let keyword is an improved version of the var keyword. It can’t be accessible outside the particular block or function.
<script> function call(){ let number = 10; Console.log(number); } Console.log(number); </script>
Output
10
ReferenceError: number is not defined

Using const

The const keyword has all the properties that are the same as the let keyword, except the user cannot update it. When users declare a const variable, they need to initialize it, otherwise, it returns an error.