PDF JS list form field names, but in order - and print to excel

This requires some advanced scripting. 

Listing the fields in the order they appear in the PDF means analyzing the field locations (i.e. page number and rectangle).  Some fields may have multiple locations, so the sorting will need to take that into account. 

 To do this, collect all the fields into an array and sort the array according to the field's geometry.  

Here's an outline for the code, note that the sorting function is missing. 

var aFlds = [];
for(var i = 0; i < this.numFields; i++)
   aFlds .push(this.getField(this.getNthFieldName(i)));

var aFieldNames = aFlds.sort(function(oFld1,oFld2){...}).map(oFld=>oFld.name);
console.println(aFieldNames.join("\n"));

An Acrobat script cannot write anything  but a PDF directly to the users file system. It can however create an attachment to the PDF and then force that attachment to open.

In this case the script should create a csv file. Most computers will open this file type in Acrobat. 

Use the "doc.createDataObject()" function

https://opensource.adobe.com/dc-acrobat-sdk-docs/library/jsapiref/doc.html#createdataobject

Then use the "doc.openDataObject()" to force the attachment to open in Excel.

https://opensource.adobe.com/dc-acrobat-sdk-docs/library/jsapiref/doc.html#opendataobject