JSFiddle - React, Tailwind, and code Playground

HTML

<div  id="pinForm">
                Signal Direction:<br/>
            <div id="pinio">
                <input type="radio" 
                             name="I_O" 
                             value="0" 
                > In<br />
               
                <input type="radio" 
                             name="I_O" 
                             value="1" 
                > Out<br />
            </div>
                Change Radio Button <br/>                 
                <input type="button" 
                             value="Swap"
                             onclick="setPinDir()"
                >
    </div>

JavaScript

//Start with Chrome browser
//Use Jquery 1.3.2 or 1.4.4 or 1.5.2
//Run the program
//Press the SWAP button multipe times, each swap alterntates which radio button is checked
//Use Jquery 1.6
//Run the program
//Press the SWAP button multiple times, the buttons swap once and then never again.

//Do the above with IE 8  and Firefox 4.01.  IE 8 seems to work with 1.6 Firefox 4.01 fails with 1.6

var pinDir=0;
function setPinDir()
{
$('input:radio[name=I_O]').filter('[value='+pinDir+']').attr('checked', true);

if(pinDir == "0")
    {
    pinDir = "1";
    }   
else
    {        
    pinDir = "0";
    }
}