function chkData(f)
{
	if(f.txtName.value=="")
	{
		alert("Please enter your name.");
		f.txtName.focus();
		return false;
	}
	var em_check=echeck(f.txtEmail.value);
	if(em_check!=true )
	{
		alert(em_check);
		f.txtEmail.focus();
		return false;
	}
	var ph_check=pcheck(f.txtPhone.value);
	if(ph_check!=true)
	{
		alert("Invalid Phone number.");
		f.txtPhone.focus();
		return false;
	}
//Checking the validity of URL
	if(f.txtUrl.value!="")
	{
		if (f.txtUrl.value.indexOf ('www', 0) == -1 || f.txtUrl.value.length < 10)
		{
			if(f.txtUrl.value.indexOf ('.com', 0) == -1 || f.txtUrl.value.length < 10) 
			{
			alert ("Enter a valid URL.")
			f.txtUrl.focus();
			return false;
			}
		}
	}
	else
	{
		alert ("Please enter Optimisation URL.")
		f.txtUrl.focus();
		return false;
	}
//End
	if(f.txtComments.value=="")
	{
		alert("Please enter your comments.");
		f.txtComments.focus();
		return false;
	}
}
//Checking the validity of email
function echeck(str) 
{
	var at="@";
	var dot=".";
	var lat=str.indexOf(at);
	var lstr=str.length;
	var ldot=str.indexOf(dot);
	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr-1)
	{
	return("Invalid E-mail ID.");
	}
	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr-1)
	{
    return("Invalid E-mail ID.");
	}
	if (str.indexOf(at,(lat+1))!=-1)
	{
	return ("Invalid E-mail ID.");
	}
	if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot)
	{
	return ("Invalid E-mail ID.");
	}
	if (str.indexOf(dot,(lat+2))==-1)
	{
	return ("Invalid E-mail ID.");
	}
	if (str.indexOf(" ")!=-1)
	{
	return ("Invalid E-mail ID.");
	}
return true;					
}
//Checking the validity of phone
function pcheck(str)
{
	var ValidChars = "0123456789";
	var IsNumber=true;
	var Char;
	if(str.length>=10 && str.length<=11) 
	{
   		for (i = 0; i < str.length && IsNumber == true; i++) 
    	{ 
    	Char = str.charAt(i); 
      		if (ValidChars.indexOf(Char) == -1) 
        	{
        	IsNumber = false;
        	}
      	}
	}
	else
	{
	IsNumber = false;
	}
return IsNumber;
}