Difference Between Var , Let and Const ?

Var: The scope of the variable defined with the keyword var is limited to the function within which it is defined . If it defined outside a function , the scope of the variable is global

Default value of var is undefined

Let : The scope of the variable defined with the keyword let is Limited to the Block defined by curly braces .
Default value of let is uninitialized

const: The scope of the variable defined with the keyword const is limited by the Curly braces block . However if a variable is defined with the keyword const it cannot be reassigned

Default value of const is uninitialized