Download a file with "AJAX" kind of POST request.

code.js

function downloadPDF(expenseClaim) {
  var payload = JSON.stringify( expenseClaim );
  var input = $("<input />").attr('type', 'hidden').attr('name', 'json').attr('value', payload);
  var form = $("<form />").attr('method', 'POST').attr('action', context+'/generatepdf2');
  form.append(input);
  form.submit();
}

pdfCommandS.subscribe(downloadPDF);