var compulsoryFieldsIn=["field_2","field_3","field_4","field_1"];
function checkForm()
{
  var checkOK=true;
  for (var i=0; i<compulsoryFieldsIn.length; i++)
  {
    var cfObj=document.getElementById(compulsoryFieldsIn[i]);
    if (cfObj!=null)
    {
      if (cfObj.type.toLowerCase()=="text")
      {
        if (cfObj.value.match(/^\s*$/)) checkOK=false;
      }
      else if (cfObj.type.toLowerCase()=="radio" || cfObj.type.toLowerCase()=="checkbox")
      {
        var tmpObj=document.getElementsByName(cfObj.name);
        var tmpCheck=false;
        for (var j=0; j<tmpObj.length; j++)
        {
          if (tmpObj[j].checked==true)
          {
            tmpCheck=true;
            break;
          }
        }
        checkOK=tmpCheck;
      }
      else if (cfObj.type.toLowerCase().indexOf("select")>=0)
      {
        if (cfObj.selectedIndex<0) checkOK=false;
      }
    }
    if (!checkOK) break;
  }
  if (checkOK) document.getElementById("subscribe").submit();
  else window.alert("Füllen Sie alle mit einem * markierten Felder aus!");
}