A variable declared using let and const,
inside a function or a code block {...}
belongs to the local scope of that function or block.
We can only access them from inside
that function or code block.
Such variables are called local variables.
Function scope and block scope are
the two types of local scopes in JavaScript.
Function Scope
A variable declared inside a function
belongs to the local scope of that function.
We can only access it from inside that function
or any inner functions.
This is known as function scope.
In the example given below,
when we access the variable greetingString from
outside the displayGreeting function,
it runs into an error.
Block Scope
A block of code is everything
inside a pair of curly braces {}.
A variable is block scoped when
it is declared using either let or const
and
is enclosed inside a block.
Such variables can only be accessed from
inside those curly braces.
In the example given above,
firstName and experience are the two variables
declared inside a block.
Therefore, they cannot be accessed
from outside the block.
Hence, when we try to access
the value of the firstName or experience
variable from outside the block,
it runs into an error.