Invio dati form ad un popup

[jesus]

function fnPopUp() {
  window.open('', 'pop_up','top=50,left=70');
  document.frm.target = 'pop_up';
  location.href='index.html';
}

<form name="frm" action="action.html" onsubmit="fnPopUp();">
  ...
</form>