<script>
var x = 3;
var y = 3;
var a = x--;
var b = --y;
document.write("a = " + a + "<br />");
document.write("b = " + b + "<br />");
document.write("x = " + x + "<br />");
document.write("y = " + y + "<br />");
/*
run:
a = 3
b = 2
x = 2
y = 2
*/
</script>