Using Prototype Javascript to get the value of a radio group

I am constantly asked how to find the value of the selected radio button in a radio group. The way I usually told people was something like this:

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print?

1	var radioGrp = document['forms']['form_name_or_id']['radio_grp_name'];
2	for(i=0; i < radioGrp.length; i++){

3	if (radioGrp[i].checked == true) {
4	var radioValue = radioGrp[i].value;

5	}
6	}

To use it you need a reference to the radio group (not just a single button), which means you need to know the form, and the radio group name. Since I use prototype for almost everything now, I decided to use it to make a simple function for this purpose. First of all, here is the function:

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print?

01	/**
02	* Returns the value of the selected radio button in the radio group, null if

03	* none are selected, and false if the button group doesn't exist
04	*

05	* @param {radio Object} or {radio id} el
06	* OR

07	* @param {form Object} or {form id} el
08	* @param {radio group name} radioGroup

09	*/
10	function $RF(el, radioGroup) {

11	if($(el).type && $(el).type.toLowerCase() == 'radio') {
12	var radioGroup = $(el).name;

13	var el = $(el).form;
14	} else if ($(el).tagName.toLowerCase() != 'form') {

15	return false;
16	}

17
18	var checked = $(el).getInputs('radio', radioGroup).find(

19	function(re) {return re.checked;}
20	);

21	return (checked) ? $F(checked) : null;
22	}

You can pass it either a form (object or id) and a radio group name, or a radio button (object or id).

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print?

1	var value = $RF('radio_btn_id');
2	var value = $RF('form_id', 'radio_grp_name');

Hopefully this will help simplify things for someone. Maybe they will eventually add something similar into prototype itself.