Replace Calculation Type Result By Script (JavaScript)

[Juan_David_Mesa_Vela]

I have this.

The Calculation Type is (Servicio al Cliente 12%), but it takes the 12% from the subtotal, but that subtotal has the taxes total included, i want to take the 12% from the subtotal of the products without the taxes.
I create this script.

this return the 12% service from the subtotal without the taxes

But i need to replace or modify the script that have by dafault the calculation type that takes the 12% from the subtotal with taxes.
How can i print the value of my script where appears the 12% of the calculation type.
The service calculation is in Payment screen.

Thank you, by the way.

[JTRTech]

Think your going about it the wrong way, sounds like you need to change the calculation to fixed amount and update with update calculation action using expressons.

[Juan_David_Mesa_Vela]

Well, i see a methot with action and rules.

I create a new Calculation Type

the action

and its rule

But when i click the button in the payment page (Automatization Command - Button Servicio 12%) nothing happen

Am i using the Call:X method in the right way? or the return value in the script is wrong?

But if i use a value directly it works, so or is the Return value of the Script or is the CALL:X method.

[Juan_David_Mesa_Vela]

The problem is solve, i create another function

and i put the Call:X method in the rule.

and now it work well

The problem was that i used String values at the begining, the last script works well if i used it in the print template, but in the rule needed a script only for number values.

[JTRTech]

The quote would make the 12 a string, you could have tried putting 12 unquoted or parsing the input as a number in the script.