The comma operator evaluates both of
its operands (from left to right) and
returns the value of the second
operand.
Source: https://developer.mozilla.org/en/JavaScript/Reference/Operators/Special_Operators/Comma_Operator
For example, the expression 1,2,3,4,5
evaluates to 5
. Obviously the comma operator is useful only for operations with side-effects.
console.log(1,2,3,4,5);
console.log((1,2,3,4,5));