Using Javascript to access a List Form Field in SharePoint Designer

An article was posted showing how to access and manipulate a List Form Field within SharePoint Designer using Javascript over at Microsoft SharePoint Designer Team Blog. The code in the article supported the following types of SharePoint 2007 form fields, but not the Radio Buttons Choice field:

Single Line of Text
Multiple Lines of Text
Number
Currency
Choice (dropdown)
Lookup (single)
Lookup (multiple)
Yes/No
So I’ve modified the function getTagFromIdentifierAndTitle and added onto it the code to allow accessing Radio Buttons Choice fields. The following is the modified function:
/*******
SharePoint Field Type  identifier     tagName    Option
---------------------  -------------- --------- ---------
Single Line of Text    TextField      input
Multiple Lines of Text TextArea       input
Number                 TextField      input
Currency               TextField      input
Choice (radio buttons) RadioButtons   input
Choice (radio buttons) RadioButtons   input       value
Choice (dropdown)      DropDownChoice select
Lookup (single)*       Lookup         select
Lookup (multiple)      SelectCandidate;
                       SelectResult   select
Yes/No                 BooleanField   input
******/
function getTagFromIdentifierAndTitle(tagName, identifier, title, option) {
  var len = identifier.length;
  var tags = document.getElementsByTagName(tagName);
  for (var i=0; i < tags.length; i++) {
    var idString = tags[i].id;
    var nameString = tags[i].name;
    // get selected radio button value only
    if (option == "value" && tags[i].type == "radio" && (identifier == "RadioButtons" && nameString.indexOf(identifier) == nameString.length - len)) {
      var tagParentHTML = tags[i].parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.innerHTML;
          if (tagParentHTML.indexOf('FieldName="'+title+'"') > -1) {
                var radioButtons = document.getElementsByName(nameString);
                var radioValue = "";
                for (var x=0; x < radioButtons.length; x++) {
                  if (radioButtons[x].checked) {
                        radioValue = radioButtons[x].parentElement.title;
                    break;
                  }
                }
        var o = document.createElement("INPUT");
        o.type = "hidden";
        o.value = radioValue;
        return o;
          }
    }
    // get radio buttons group
    if (tags[i].type == "radio" && (identifier == "RadioButtons" && nameString.indexOf(identifier) == nameString.length - len)) {
      var tagParentHTML = tags[i].parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.innerHTML;
          if (tagParentHTML.indexOf('FieldName="'+title+'"') > -1) {
                return document.getElementsByName(nameString);
          }
    }
        // all other input or select type
    else if (tags[i].title == title && (identifier == ""  idString.indexOf(identifier) == idString.length - len)) {
      return tags[i];
    }
  }
  return null;
}

Here is how you would use the function above for Radio Buttons:
// to get the selected radio button and its value
var myRadioButtonsSelected = getTagFromIdentifierAndTitle("input","RadioButtons","MyFieldName","value");
var myRadioButtonsValue = myRadioButtonsSelected.value;

// to get the array for radio buttons
var myRadioButtonsArray = getTagFromIdentifierAndTitle("input","RadioButtons","MyFieldName");
for (var x=0; x < myRadioButtonsArray.length; x++) {
    // do whatever you like here...
    // for example:
    myRadioButtonsArray[x].parentElement.onclick = function(){alert(myRadioButtonsArray[x].value);};
}

The original post can be found here: Using Javascript to Manipulate a List Form Field
For a basic function, you could also check out Boris Gomiunik’s Blog for another post about referencing SharePoint form fields using Javascript.