Javascript variables are a container for storing values. In javascript, there are three types of variables let
const
and var
.
var
variable has a functional scope which means that variables that are defined inside a function can only be accessible within the function.
var
type variables don't have block scope they are accessible outside of the block
var
type variables override var
type variable which has the same name in their scope.
Redeclaring a let
or const
variable with var
is not allowed in the same scope and in functional scope
let
type variable has the same functional scope as var
variable but they also have Block sope
let
type variable defined in Block
are NOT
accessible outside of Block
as shown in the example.
Redeclaring a let
variable with type let
or const
or var
is not allowed in the global. The compiler will throw an error
Redeclaring a let
variable with type let
or const
or var
is not allowed in the block. The compiler will throw an error
Redeclaring a let
variable with type let
or const
or var
is not allowed in the functional scope. The compiler will throw an error
Now let's talk about const
variables. As the name suggests we cannot reassign a value to the const
variable.
const
type variable also have functional
and Block
level scope.
const
type variable defined in Block
is NOT
accessible outside of block as shown in the example.
Redeclaring a const
variable with type let
or const
or var
is not allowed in the global. The compiler will throw an error
Redeclaring a const
variable with type let
or const
or var
is not allowed in the block. The compiler will throw an error
Redeclaring a const
variable with type let
or const
or var
is not allowed in the functional scope. The compiler will throw an error
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