If a checkbox is selected can it perform a calculation?

[Guest]

I would like to have a check box field and if selected it would return a value in another field. Eg. if selected take the value in field "subtotal" and multiply it by 0.05. return that value in field "GST". Is this possible.

[try67]

Yes, but it's better to do it from the calculation event of the target field ("GST") then from the check-box itself.

What should be the value of this field if the box is not ticked, though?

[Guest]

The value would be $0.00

[try67]

OK, then use this code as the custom calculation script (you'll just need to adjust the names of the fields involved to match the actual names in your file):

var subtotal = Number(this.getField("subtotal").value);
event.value = (this.getField("CheckBox1").value=="Off") ? 0 : subtotal * 0.05;

[Guest]

Sorry, I am not very familiar with code. Am I pasting the code into the custom calculation script of the GST field? I did and the field names you used are exactly what mine are titled (GST, Subtotal and CheckBox1) but when I check CheckBox1 nothing happens and the GST field does not return a value.

[try67]

Yes, that's basically it, but be aware that JS is case-sensitive. So if the field is called "Subtotal" and in the code you have "subtotal" it won't work. You should also check the JS Console (Ctrl+J) for any error messages.