jquery append to input value

Question

This is the last problem i have with my form (hopefully)

What I want to do is append the var size to my hidden input called my-item-name

I have tried adding this

form.find('[name=my-item-name]').append(size.val());

but it doesn't work.

What is the correct way to append the size val to the input?

<form method="post" action="" class="jcart">
    <fieldset>
        <input type="hidden" name="jcartToken" value="13823c48f896c49403465fcce9f135ac" />

        <input type="hidden" name="my-item-id" value="12" />
        <input type="hidden" name="my-item-price" value="15.99" />
        <input type="hidden" name="my-item-url" value="http://yahoo.com" />
        <input type="hidden" name="my-item-name" value="Operation Braveheart hooded sweatshirt" />
        <ul>
            <li>
                <select name="my-select" id="foo12">
                    <option value='Small'>Small</option>
                    <option value='Medium'>Medium</option>
                    <option value='Large'>Large</option>
                    <option value='X-Large'>X-Large</option>
                </select>
            </li>
            <li>Price: $<span id="price12" class="price">15.99</span></li>
            <li>
                <label>Qty: <input type="text" name="my-item-qty" value="1" size="3" /></label>

            </li>
        </ul>

        <input type="submit" name="my-add-button" value="add to cart" class="button" />
    </fieldset>
</form>                
<script type="text/javascript">
    var item_prices_by_size12 = { "Small": { "Price": "15.99", "ItemId": "9-1" },"Medium": { "Price": "16.99", "ItemId": "9-2" },"Large": { "Price": "17.99", "ItemId": "9-3" },"X-Large": { "Price": "18.99", "ItemId": "9-4" }};
    $(function() {

        $('#foo12').change(function() {

            var form = $(this).parents('form');

            // Size is whatever the value the user has selected
            var size = $(this).val();

            // Determine the correct price and item ID based on the selected size
            var price12  = item_prices_by_size12[size].Price,
            itemId = item_prices_by_size12[size].ItemId;

            form.find('#price12').text(price12);

            form.find('[name=my-item-price]').val(price12);

            // Update the item ID
            form.find('[name=my-item-id]').val(itemId);

            form.find('[name=my-item-name]').append(size.val());

        });
    });
</script>

Answer 1

append: "Insert content, specified by the parameter, to the end of each element in the set of matched elements."

What you want to do is append to the value I think?

var value = form.find('[name=my-item-name]').val();
form.find('[name=my-item-name]').val(value + size); 

Answer 2

If you mean concatenate:

  $('[name=my-item-name]').val($('[name=my-item-name]').val()+""+size);

(Reading your code size is already the val of the object so you can't call size.val())