Hi,I am working on a php ajax dropdownlist.
What i am trying,When a user select january month it show 31 days similarly in march 31,april 30,may 31 n december.
in feb month it should take leap year.
Need suggestion

Are you just looking for a date picker to attach to a textbox or is there some other need for a month/day drop down list. If you look at jQuery there are a bunch of date picker apps already built.

If you truly need a Month and Day drop down box I would create an array with the number of days in each month. The only special circumstance would be for February. I would then use this array to build and replace the options in the Day drop down list. For February you would have one additional calculation to determine if it is leap year.

I would still look at jQuery no matter which option you use, as it makes dealing with DOM elements a lot easier.

A quick search turned up this page with some available jQuery date picker add-ons.