.java

var els = form.elements
for (var i = 0; i < len; i++) {
  var el = els[i];
  if (el.name === "") {
    continue;
  }
//only add successfull controls
  if (!el.disabled) {
    switch(el.type) {
      case 'button':
      case 'submit':
      case 'reset':
      case 'image':
      case 'file':
        break;
      case 'select-one':
        if (el.selectedIndex >= 0) {
          addField(el.name,...);
        }
        break;
      case 'select-multiple':
       ...
      case 'checkbox':
      case 'radio':
//only checked radio- an checkboxes are successfull controls
        if (el.checked) {
          addField(el.name, el.value || 'on');
        }
        break;
      default:
//this is for any input incl. 'text', 'password', 'hidden', 'textarea'
        var nodeName = el.nodeName.toLowerCase();
        if (nodeName === "input" || nodeName === "select" ||
            nodeName === "object" || nodeName === "textarea") {
            addField(el.name, el.value);
        }
        break;
    }
  }
}
//concatenate the array
return qString.join("");