javascript date difference in php

function checkdate()
{
t1="1/1/2006" ;

t2="25/1/2006";

//Total time for one day
var one_day=1000*60*60*24;
//Here we need to split the inputed dates to convert them into standard format
var x=t1.split("/");
var y=t2.split("/");
//date format(Fullyear,month,date)
var date1=new Date(x[2],(x[1]-1),x[0]);
var date2=new Date(y[2],(y[1]-1),y[0])
var month1=x[1]-1;
var month2=y[1]-1;
//Calculate difference between the two dates, and convert to days
Diff=Math.ceil((date2.getTime()-date1.getTime())/(one_day));
document.write(Diff);
//_Diff gives the diffrence between the two dates.
}