var
, let
, and const
are probably the first words you hear about while learning JavaScript. Since the let
keyword has been already explained in this Edpresso shot, and var
doesn’t deserve a separate article yet, let’s find out what const
is:
const
const
is a JavaScript keyword introduced by ES6 that doesn’t have a previous equivalent.let x = 10;
const x = 10; //This is not possible.
const
creates block-scoped and read-only reference that cannot be reassigned.const x = 10;x = 15;console.log(x); //This is will throw an error because//x is read-only
const
identifiers in all-uppercase (to vary them from let
variables).const TEMP_X = 10;
const
keyword has to be initialized immediately. A const
keyword without an assigned value will cause a syntax error.const X; //This is not possible.