title: Magento custom option - clear input field issue
body: <p>I add two radio buttons in the product view custom options. and one text input field dependent on radio buttons. So when the first radio is check the first text is hide and I add this characters: "-------" to the value attribute in input text. When the second radio button is check I need to display the text input field and remove the value "-------". </p>
  
  <p>To add the value to the text input I use javascript:
   <code>jQuery(".product-options dd input.input-text").attr('value', '--------');</code></p>
  
  <p>To remove the value I use : <code>jQuery(".product-options dd input.input-text").attr('value', '');</code></p>
  
  <p>Everything is ok until press Add to cart button, when I press add to cart button I have this: <code>"Please specify the product's required option(s)."</code></p>
  
  <p>My code is: </p>
  
  <pre><code>if (jQuery('.product-options .display ul li:nth-child(1)').find('input').is(':checked')) {
                          jQuery(".product-options dd input.input-text").attr('value', '--------');
                          jQuery(".product-options dd input.input-text").addClass('validation-passed');
  }
  
  jQuery('.product-options .display ul li:nth-child(1)').find('input').change(function(){
      if (jQuery(this).is(':checked')) {
                          jQuery(".product-options dd input.input-text").attr('value', '--------');
                          jQuery(".product-options dd input.input-text").addClass('validation-passed');
      }
  })
  
  jQuery('.product-options .display ul li:nth-child(2)').find('input').change(function(){
      if (jQuery(this).is(':checked')) {
              jQuery(".product-options dd input.input-text").attr('value', '');
      }
  })
  </code></pre>
  
  <p>So what I want is to add a the default value to the text input field when first radio is check and the input text field is hidden to pass the validation and remove this value when the second radio is check and the text input field is show.</p>
  
  <p>Thank you</p>