The script is a [FONT=Courier New]for[/FONT] loop. The loop parameters are as follows:
- Declaration & initialisation
- Logical check
In other words, the 1st parameter of the loop declares and initialises a variable ([FONT=Courier New]fl[/FONT]) to 10. The loop then executes the 2nd parameter, which is a logical check. It basically says "if [FONT=Courier New]FL[/FONT] is less-than-or-equal-to 150". If this statement is a [FONT=Courier New]true[/FONT] statement, it will execute the body of the loop ([FONT=Courier New]sum = sum + fl[/FONT]) and will then proceed to the 3rd and final parameter of the loop, which is an increment.
This code can also be written as:
var sum = 0;
for (fl=10; fl<=150; fl+= 5)
sum += fl;
document.write (sum += fl);
This code doesn't really make much sense, but it may be part of a larger file that we can't see.