How to trigger onShow callback for Keith Wood jQuery datepicker?

Using Keith Wood's datepicker how can I trigger a callback before the datepicker is shown so I can set the picker's parameters? Using the code below the callback (alert) is shown on page ready and开发者_StackOverflow社区 not before the datepicker is shown.

$(function(){
   $( ".inputDatePick").datepick({ onShow: alert('on show callback') });
});

....

<input type="text" class="inputDatePick" />

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doh! the correct syntax for a callback is a function :

$(function(){
   $( ".inputDatePick").datepick({ onShow: function () { alert('on show callback') } });
});