# [NTG-context] Widgets: Any good examples for developing JS-enabled PDFs that calculate?

Hans Hagen j.hagen at xs4all.nl
Mon Nov 18 19:56:14 CET 2019

```On 11/18/2019 4:15 PM, Henning Hraban Ramm wrote:
> Hi,
> I didn’t check your example, but I remember that JScode did only work if there’s also a JSpreamble.
> Also the "used now" keyword (see Hans’ message) is essential.

i don't think so, the code is in the file and one can see that arobat
sees it too but using a preamble and functions is more efficienty
(reuse) and easier to trace

the problem with calculate is that there are also settings related to it
(plus some built-in addition stuff, at least that's what i see in the
viewer preferences and such, which is likely to interfere)

(and calculate doens't seem to be called at all)

> HTH. Sorry, no time for further investigation.
>
> Hraban
>
>> Am 2019-11-17 um 21:13 schrieb Paul Mazaitis <pm39 at andrew.cmu.edu>:
>>
>>
>> Hi everyone,
>>
>> First: apologies for the long email; this got a little complicated.
>>
>> Summary: there may be a bug in setting up calculate field for widgets?
>>
>> Parts:
>>
>> - calculator.tex
>> - A M(N)WE
>> - The MWE Only Sort of Works
>>
>> # calculator.tex
>>
>> On 13 Nov 2019, at 10:26, Pablo Rodriguez wrote:
>>
>>> Hi Paul,
>>
>>> I wonder whether
>>> tex/texmf-context/doc/context/examples/calculator/calculator.tex from
>>> the ConTeXt Suite might be what you look for.
>>>
>>> Just in case it helps,
>>
>> It does (and is quite something!); it's not quite what I need, though. I'd like to take advantage of the internal _calculate_ event when a field updates - the calculator.tex PDF appears to be entirely programmatically event driven?
>>
>> (Which could certainly work for my application, but I want to try to keep this as simple for the user as possible.)
>>
>>> Pablo
>>
>> # A M(N)WE
>>
>> Here's a Minimal Working Example, with some caveats:
>>
>> --- begin MWE ---
>>
>> \usemodule[fields]
>>
>> \starttext
>>
>> \setupinteraction [state=start]
>>
>> \startJScode{tallyUp}
>>   var a_fld = this.getField("A");
>>   var b_fld = this.getField("B");
>>   event.value = a_fld.value + b_fld.value;
>> \stopJScode
>>
>> \setupfield[numField][reset,horizontal]
>>         [height=2pc,rulethickness=1pt,framecolor=lightgrey]
>>
>> \setupfield[totalField][reset,horizontal]
>>         [
>>         height=2pc,
>>         rulethickness=1pt,
>>         framecolor=lightgrey,
>>         calculate=JS(tallyUp),
>>         ]
>>
>> \definefield[A][line][numField][]
>> \definefield[B][line][numField][]
>>
>> \definefield[Total][line][totalField][]
>>
>> A: \field[A]
>>
>> B: \field[B]
>>
>> \blank[big]
>>
>> Total: \field[Total]
>>
>> \stoptext
>>
>> ---  end MWE  ---
>
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