Core JavaScript 1.5 Reference:Operators:Special Operators:Comma Operator
From MDC
Contents |
[edit] Summary
The comma operator evaluates both of its operands and returns the value of the second operand.
| Operator | |
| Implemented in: | JavaScript 1.0 |
| ECMA Version: | ECMA-262 |
[edit] Syntax
expr1, expr2
[edit] Parameters
-
expr1,expr2 - Any expressions.
[edit] Description
You can use the comma operator when you want to include multiple expressions in a location that requires a single expression. The most common usage of this operator is to supply multiple parameters in a for loop.
For example, if a is a 2-dimensional array with 10 elements on a side, the following code uses the comma operator to increment two variables at once. The code prints the values of the diagonal elements in the array:
for (var i=0, j=9; i <= 9; i++, j--)
document.writeln("a["+i+"]["+j+"]= " + a[i][j]);