JQuery :: Accessing Button Attributes OnClick Event Handler

I am have an MVC app that generates a list of rows, of which one of the columns is a button. Here is the rendered HTML for the buttons:
<input
id
="btnUpdate21"
type
="submit"
value
="Approve"
synchId
="21"
/>
<input
id
="btnUpdate22"
type
="submit"
value
="Approve"
synchId
="22"
/> .....

Following is my selector that I use to bind the buttons to my click event:
<script
type
="text/javascript"
charset
="utf-8"
>
$(document).ready(function
() {
$('input[id^="btnUpdate"]'
).click(promptForSynchDate);
});

I have been trying to access the button Id, though what I really need is the attribute synchId, to use inside of a modal. I have so far been unable to access either one of them. My modal works fine. But the value of either attribute is always "undefined".

Here is my click event handler: (I stuck the alert in there just for debug purposes)
function promptForSynchDate() {
$(document).ready(
function () {
var test1 = $(this).attr('id');
alert(
'test1 is : ' + test1);
$(
'#approve-synch').dialog({ .....