How to show jQuery DatePicker explicitly using JavaScript

I want the Datepicker to show on a particular event which can be triggered when a particular value is chosen in开发者_Python百科 a drop down.

In other words I want to write an onchange function for the drop down and if the value matches, I could call the function to show the calendar. but the function showDatepicker as described in the docs page doesn't work:

http://docs.jquery.com/UI/Datepicker/showDatepicker

Try running the following command in firebug console at the following page:

http://jqueryui.com/demos/datepicker/

$("#datepicker").showDatepicker();

It should work as described in the Docs, but it doesn't

I use $("#datepicker").datepicker("show");