Comma Operator (,)
Causes two expressions to be executed sequentially.
expression1, expression2
Arguments
expression1
Any expression.expression2
Any expression.
Remarks
The , operator causes the expressions on either side of it to be executed in left-to-right order, and obtains the value of the expression on the right. The most common use for the , operator is in the increment expression of a for loop. For example:
var i, j, k;
j=25;
for (i = 0; i < 10; i++, j++) {
k = i + j;
}
The for statement only allows a single expression to be executed at the end of every pass through a loop. The , operator is used to allow multiple expressions to be treated as a single expression, thereby getting around the restriction.