Object is null for radio value created by PHP

[Wdblazer]

I have a unique problem with one of my php form page and the javascript that passes the radio value. If the ELSE function in my php runs off and print 3 radio options, I have no problem passing the value in the URL. However if the IF part runs off and print only one radio option, I got the error

'document.forms.newhappening.EventType.0.checked' is null or not an object

function sendRequest() {
	 if(document.forms["newhappening"].EventType[0].checked==true)
	 	{
			var theEventType = "Public";
		}
		
	 if(document.forms["newhappening"].EventType[1].checked==true)
	 	{
			var theEventType = "Friend";
		}
			 if(document.forms["newhappening"].EventType[2].checked==true)
	 	{
			var theEventType = "Personal";
		}
	new Ajax.Request("newhappeningresult.php", 
	{ 
		method: 'post', 
		postBody: 'EventName='+ $F('EventName')+'&EventLocation='+ $F('EventLocation')+'&EventDetail='+ $F('EventDetail')+'&EventTimeHour='+ $F('EventTimeHour')+'&EventTimeMin='+ $F('EventTimeMin')+'&EventTimeShift='+ $F('EventTimeShift')+'&EventType='+ theEventType +'&EventDate='+ $F('EventDate'),
		onComplete: showResponse 
	});
}
function showResponse(req){
	$('newhappening').innerHTML= req.responseText;
}

<form id="newhappening" onSubmit="return false;">
<?php
	if ($userID == "Public")
	{
			echo "<input type=RADIO name=\"EventType\" value=\"Public\" checked/>Share with the everyone";
			echo "<br>";
	}
	
	else
	{
			echo "<input type=RADIO name=\"EventType\" value=\"Public\" />Share with the public";
			echo "<br>";
			echo "<input type=RADIO name=\"EventType\" value=\"Friend\" />Share with all my friends";
			echo "<br>";
			echo "<input type=RADIO name=\"EventType\" value=\"Personal\" checked/>Personal";
			echo "<p>";
	}
?>
    <input type="submit" value="Submit" onClick="sendRequest()">
  </p>
</form>

[clueful]

However if the IF part runs off and print only one radio option, I got the error

'document.forms.newhappening.EventType.0.checked' is null or not an object

When only one element exists, there is no array and indexing is not possible. You must detect that situation. I can't test this but you can learn from it:

function sendRequest( form ) 
{
 var group = form.EventType, theEventType = "";
 
 if( group.length )
 {
   if( group[0].checked )
     theEventType = "Public";   
		
   if( group[1].checked )
     theEventType = "Friend";   

   if( group[2].checked )
     theEventType = "Personal";   
 }
 else
  if( group.checked )
   theEventType = "Public";

	new Ajax.Request("newhappeningresult.php", 
	{ 
		method: 'post', 
		postBody: 'EventName='+ $F('EventName')+'&EventLocation='+ $F('EventLocation')+'&EventDetail='+ $F('EventDetail')+'&EventTimeHour='+ $F('EventTimeHour')+'&EventTimeMin='+ $F('EventTimeMin')+'&EventTimeShift='+ $F('EventTimeShift')+'&EventType='+ theEventType +'&EventDate='+ $F('EventDate'),
		onComplete: showResponse 
	});
}

Call the function like this:

<input type="submit" value="Submit" onClick="sendRequest( this.form )">

[Wdblazer]

Great, so thats why I been getting a null object. I don't quite understand your code, it would be great if you could explain it I work around the problem by detecting if there is an array length and IF ELSE accordingly. Thanks, how do I put a resolved tag on this thread?

var radiolength = document.forms["newhappening"].EventType.length;

	if (radiolength)
	{
	 if(document.forms["newhappening"].EventType[0].checked==true)
	 	{
			var theEventType = "Public";
		}
		
	 if(document.forms["newhappening"].EventType[1].checked==true)
	 	{
			var theEventType = "Friend";
		}
	if(document.forms["newhappening"].EventType[2].checked==true)
	 	{
			var theEventType = "Personal";
		}
	}
	else
	{
		var theEventType = "Public";
	}