Difference between dates in terms of date,month and year

function GetdateDiff()

{

var dt1= document.getElementById('txtdate1').value;

var dt2= document.getElementById('txtdate2').value;

var delimeter ='/';

var data1=dt1.split(delimeter);

var data2=dt2.split(delimeter);

var Tdat=data1[0]-0;

var TMonth=data1[1]-0;

var TYear=data1[2]-0;

var Odat= data2[0]-0;

var OMonth=data2[1]-0;

var OYear= data2[2]-0;

if(TYear > OYear)

{

this.Calculate(Tdat,TMonth,TYear,Odat,OMonth,OYear)

}

else if(TYear == OYear)

{

if(TMonth > OMonth)

{

              this.Calculate(Tdat,TMonth,TYear,Odat,OMonth,OYear)

}

else if(TMonth == OMonth)

{

if(Tdat >Odat)

{

 this.Calculate(Tdat,TMonth,TYear,Odat,OMonth,OYear)

}

else

{

 this.Calculate(Odat,OMonth,OYear,Tdat,TMonth,TYear)

}

}

else

{

 this.Calculate(Odat,OMonth,OYear,Tdat,TMonth,TYear)

}

}

else

{

this.Calculate(Odat,OMonth,OYear,Tdat,TMonth,TYear);

}

}

function Calculate(Tdat,TMonth,TYear,Odat,OMonth,OYear)

{

var M311="1,3,5,7,8,10,12";

var M300="4,6,9,11";

var M31=M311.split(',');

var M30 =M300.split(',');

var Fdate;

var Fmonth;

var Fyear;

if(Tdat >= Odat)

{

Fdate = Tdat - Odat;

}

else

{

for(i=0 ; i<>

{

if( TMonth ==M31[i])

{

Tdat = Tdat + 31;

break;

}

}

for(i=0; i<>

{

if( TMonth ==M30[i])

{

Tdat = Tdat + 30;

break;

}

}

if(TMonth==2)

{

  if((TYear % 4)==0)

  {

        if(Tdat > 29)

{

  alert('Invalid date')

  return;

}

Tdat=Tdat + 29;

  }

  else

  {

      if(Tdat > 28)

{

  alert('Invalid date')

  return;

}

  Tdat=Tdat+28;

  }

}

Fdate=Tdat-Odat;

TMonth = TMonth - 1;

}

if(TMonth >= OMonth)

{

Fmonth = TMonth - OMonth ;

}

else

{ 

   Fmonth = TMonth - OMonth + 12;

TYear=TYear-1;

}

Fyear=TYear - OYear;

alert('Year :'+Fyear + '\n Month :' + Fmonth + '\n Day :' + Fdate);

}