Available in Chrome 41+
Lexical declarations introduce new declaration forms for defining variables using the
let
and
const
keywords
let
is similar to
var, but defines a variable
limited in scope
to the block,
statement or expression in which it is used. This differs from the
var
keyword, which defines variables globally or local to a function regardless of block scope.const
is similar to
let, but for
constant declarations that are read-only.