Scan a document for collecting the values of some fields

I created a document (I don't know how to upload a pdf, therefore you can access a sample via Dropbox : https://www.dropbox.com/s/fni2eur4t1w48qa/Data_collecting%20.pdf?dl=0) of several pages and I need to extract the value of a field which can appear on some of the pages.

These fields are named:

Source.0

Source.1

Source.2

etc.

Page one can start with the field Source.2

the following page can be free of such a field

The field Source.8 may appear on page 3

etc.

I am trying to scan each page for finding a field starting with "Source." and if found, to copy its value to another field starting with "Result." but with the same index :

Result.3 value = Source.2 value

Result.10 value = Source.10 value

etc.

Please pay attention : the fields "Source." contain fixed references and the displayed pages are issued from templates. Therefore, I need to know which reference fields appear ont the displayed pages, and then capture their value. The list of "Result" will show part of the fields with a value, and the others must stay empty.

Here below is the beginning of my story... but I miss too much knowledge to continue...

Can someone help me to finalize it ?

Many thanks in advance.

*********************************************************************

ATTEMPT to display the value in app.alert (!!! infinite loop !!!

**********************************************************************

var
nameField="";

for (var a
= 0; a < this.numPages; a++) {

for (var i
= 0; i < this.numFields; i++) {

              var
nameField=this.getNthFieldName(i);

              var f = this.getField(nameField);

              var str=nameField;

              var OK =
str.indexOf("Source.");

              if (OK > -1) {

                            app.alert(this.getField(nameField).value);

                                           //break;

                            }

              }

}