title: Disabling and enabling button submit based on radio input conditions
body: <p>I would like to disable an input field from being click-able if user hasn't selected a radio button. 
  Here is the simple HTML form:</p>
  
  <pre><code>&lt;form method="POST"&gt;
      &lt;input type='radio' name='a' value='a' id='checkMe' /&gt; a 
      &lt;input type='radio' name='a' value='b' id='checkMe' /&gt; b  
      &lt;input type='radio' name='a' value='c' id='checkMe'  /&gt; c    
      &lt;input type='submit' value='choose' id='choose' disabled="disabled"/&gt;    
  &lt;/form&gt;
  </code></pre>
  
  <p>Now, I made this js, to see if one of the inputs is selected, then the <code>disabled="disabled"</code> part should be revered, but that is now the case in this JavaScript code </p>
  
  <pre><code>if(document.getElementById('checkMe').checked) {
     document.getElementById('choose').disabled=false;
  }  
  </code></pre>
  
  <p>Here is the online demo. <a href="http://jsfiddle.net/2HC6s/" rel="nofollow">http://jsfiddle.net/2HC6s/</a></p>