You forgot about the difference between PHP month numbering and JavaScript month numbering. PHP counts months as the Japanese do: January = 1, February = 2, etc. JavaScript is different. In JavaScript, January is month 0, February is month 1, etc.

You can take these lines
// here’s the PHP code that spawn out the server local time

// now we represent the server time as javascript date
var server = new Date(, , , , , ).getTime();
and replace them with
// here’s the PHP code that spawn out the server local time

// now we represent the server time as javascript date
// note we subtract 1 from the month
var server = new Date(, - 1, , , , ).getTime();
or if you want UTC you can just do this
// here’s the PHP code that spawn out the server local time

// now we represent the server time as javascript date
var server = ;
Note: none of my code has been tested!

Thank you.