var foo [= value [, foo2 [, foo3 … [, fooN]]]];
let bar [= value [, bar2 [, foo3 … [, barN]]]];
const baz = value [, baz2 = value2 [, … [, bazN = valueN]]];
See also:
Declaration
Assignment
Declaring and initializing constants
Modifying constants
Reassigning constants
Undefined
Mathematic operations and assignment