The comma operator evaluates both of its operands (from left to right) and returns the value of the most right-hand operand.

```
var a = (7, 5);
a; //5

var x, y, z
x = (y=1, z=4);
x; //4
y; //1
z; //4
```
```
students.map(s => (s.archived = true, s))
```