JavaScript for loop won't work

The following code results in the error
Unexpected token `for'

I'm not a JavaScript expert, but it looks valid to me:

Code:

---

for (i=1;i<=10;i++)
    {
        // Do something
    }

---

Is this the whole script?

My bad. From what I've heard on the DevDays, I just assumed that I could mix JavaScript and QML as I wanted. Wrapping it with a function does the trick.