In the explanation for Example 6 there is sentence:
In the following line, you add the value of the radio button the user has selected to your message string:
compSpec = compSpec + findSelectedSpeedValue();
compSpec = compSpec + "\nWith the following additional components:\n";
There is actually getSelectedSpeedValue() function not findSelectedSpeedValue()
Also right below that, there is:
It’s here that you loop through each element on the form using myForm[controlIndex], which returns a reference to the element object stored at the
controlIndex index position.
You’ll see that in this example the element variable is set to reference the object stored in the myForm collection at the index position stored in variable controlIndex.
In our example in actual book (5th) we don't have variable called controlIndex.