User Guide

302 Chapter 2: ActionScript Language Reference
The following example shows that curly braces ({}) are not necessary if only one statement will
execute:
var sum:Number = 0;
for (var i:Number = 1; i<=100; i++)
sum += i;
trace(sum); // output: 5050
See also
++ (increment), –– (decrement), for..in, var, while, do while