title: Set input text-field "expiration date" one year after "effective date"
body: <p>I have two input text-fields, an "effective date" and an "expiration date."  I'm using jquerytool's dateinput function as the date-picker.</p>
  
  <p>Question:
  When the "effective date" is picked, I'd like the "expiration date" to be one-year from the "effective date" and to set that value to the "expiration date" text-input field.</p>
  
  <p>I cannot seem to get this all working...</p>
  
  <pre><code>&lt;script&gt;
  
  $(document).ready(function() {
  
    $(":date").dateinput({
      format: 'mmmm dd, yyyy', // the format for example: 'October 04, 2012'
    });
  
  function expiration (){
    // date calculations here?...
    ...
    document.getElementById('expiration').value = expirationDate;
  
  }
  &lt;/script&gt;
  
  
  &lt;input type="date" name="effective" id="effective" onChange="expiration()" /&gt;
  
  &lt;input type="date" name="expiration" id="expiration" /&gt;
  </code></pre>