Before es6 VAR
was the King. We used var in everywhere we wants to declare a variable

var
variables can be re-declared and updated

Now we divide var with two different types one CONST & other LET
CONST
is declared for those value which will not changed anytime! Or will not be updated at any point. const
cannot be updated or re-declared, this will lead you to an error you if try

We use LET when their is a change of updating the variable

LET can be updated but not re-declared. This will give a error you can’t run code

So in es6 we use LET & CONST not Var!
Do you knew this before ?