getting value of radio buttons

I'm trying to come up with some Javascript that will display a text field
if a certain value is selected in a related radio button group. Something
like this:

<script type="text/javascript">

function showfield(id){
var sourceid='type_'+id;
var targetid='update_'+id;

var value=getRadioValue(sourceid);

if (value == 'c'){
document.getElementById(targetid).style.display = 'block';
}else{
document.getElementById(targetid).style.display = 'none';
}

}

function getRadioValue(obj){
if (!obj){
return;
}
for(var i=0;i<obj.length;i++){
if (obj[i].checked){
return(obj[i].value);
break;
}
}
return "unknown";
}

<script>

<input name="type_1" id="type_1" type="radio" value="a"
onChange="showField('1')">a
<input name="type_1" id="type_1" type="radio" value="b"
onChange="showField('1')>b
<input name="type_1" id="type_1" type="radio" value="c"
onChange="showField('1')>c

<div style="display: block;" id="update_1"><textarea name="update_1">
</textarea></div>



I'd like to be able to have the textarea appear only when choice 'c' is
selected. My problem is in the getRadioValue function. obj.length
doesn't appear to be returning anything, ever. Is the problem in how I'm
getting the object? Or somewhere else?

Randy Webb <HikksNotAtHome (AT) aol (DOT) com> wrote in
news:ILadnfBQ9eTgXazZ4p2dnA (AT) comcast (DOT) com:

URL: http://www.jibbering.com/faq/faq_not...ess.html#faBut

Will show you how to get the value of a Radio Button.

That's pretty much what I'm doing, but with a named id. Not working
though.

Tony Rice said the following on 4/3/2006 7:58 PM:

I'm trying to come up with some Javascript that will display a text field
if a certain value is selected in a related radio button group. Something
like this:

<URL: http://www.jibbering.com/faq/faq_not...ess.html#faBut >

Will show you how to get the value of a Radio Button.
--
Randy
comp.lang.javascript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

Tony Rice said the following on 4/3/2006 8:44 PM:

Randy Webb <HikksNotAtHome (AT) aol (DOT) com> wrote in
news:ILadnfBQ9eTgXazZ4p2dnA (AT) comcast (DOT) com:

URL: http://www.jibbering.com/faq/faq_not...ess.html#faBut

Will show you how to get the value of a Radio Button.

That's pretty much what I'm doing, but with a named id. Not working
though.

Give them a name.

--
Randy
comp.lang.javascript FAQ - http://jibbering.com/faq & newsgroup weekly
Javascript Best Practices - http://www.JavascriptToolbox.com/bestpractices/

Randy Webb <HikksNotAtHome (AT) aol (DOT) com> wrote in
news:ILadne1Q9eQgXKzZ4p2dnA (AT) comcast (DOT) com:

Tony Rice said the following on 4/3/2006 8:44 PM:
Randy Webb <HikksNotAtHome (AT) aol (DOT) com> wrote in
news:ILadnfBQ9eTgXazZ4p2dnA (AT) comcast (DOT) com:

URL: http://www.jibbering.com/faq/faq_not...ess.html#faBut

Will show you how to get the value of a Radio Button.

That's pretty much what I'm doing, but with a named id. Not working
though.

Give them a name.

I'm using document.getElementById, like so:

<script type="text/javascript">

function showfield(id){
var sourceid='type_'+id;
var targetid='update_'+id;

var value=getRadioValue(sourceid);

if (value == 'c'){
document.getElementById(targetid).style.display = 'block';
}else{
document.getElementById(targetid).style.display = 'none';
}

}

function getRadioValue(obj){
if (!obj){
return;
}
for(var i=0;i<obj.length;i++){
if (obj[i].checked){
return(obj[i].value);
break;
}
}
return "unknown";
}

<script>

<input name="type_1" id="type_1" type="radio" value="a"
onChange="showField('1')">a
<input name="type_1" id="type_1" type="radio" value="b"
onChange="showField('1')>b
<input name="type_1" id="type_1" type="radio" value="c"
onChange="showField('1')>c

<div style="display: block;" id="update_1"><textarea name="update_1">
</textarea></div>