jQuery: How can select clicked element in table without define unique id for each element

I have table (that generated by server) below. I want to get input element value class="itemQuantity" of clicked row. I write jQuery code but he missing "this" of clicked element.

<script type="text/javascript">
$(document).ready(function() {
    $('.updateButton').click(function() {
        alert($('.itemQuantity').val());
    });
});
</script>

How can I do it with jQuery (I 开发者_如何学Cthinking to use this and not create id for each element, but I have low knowledge in jQuery).

Thanks, Yosef

<table id="items">
<tr>
<th>item id</th>
<th>item name</th>
<th>item quantity</th>
<th>item update</th>
</tr>
<tr>

<td class="itemID">
1
</td>

<td class="itemName">
Ferari
</td>
<td >
<input class="itemQuantity" type="text" size="4" />
</td>
<td>
<button class="updateButton">update item</button>
</td>
</tr>
<tr>

<td class="itemID">
2
</td>

<td class="itemName">
Fiat
</td>
<td >
<input class="itemQuantity" type="text" size="4" />
</td>
<td>
<button class="updateButton">update item</button>
</td>
</tr>

<tr>

<td class="itemID">
3
</td>

<td class="itemName">
Hundai
</td>
<td >
<input class="itemQuantity" type="text" size="4" />
</td>
<td>
<button class="updateButton">update item</button>
</td>
</tr>    
</table>     

$(document).ready(function() {
$('.updateButton').click(function() {
    alert($(this).closest('tr').find('.itemQuantity').val());
});
});

In jQuery event handlers "this" will refer to the DOM element that is the source of the event. So in your click() function you can use either this or $(this) if you need a wrapped object.

If your HTML is fixed you can also achieve the same result with parent():

<script type="text/javascript">
  $(document).ready(function() {
    $('.updateButton').click(function() {
      alert($(this).parent().parent().find('.itemQuantity').val());
    });
  });
</script>