How do I verify a PAN Card number?

/*  This function validates for PAN Card No.*/
function pan_card(textObj) 
{
	var regpan = /^([a-zA-Z]){5}([0-9]){4}([a-zA-Z]){1}?$/;
	/*C - Company 
	P - Person 
	H - HUF(Hindu Undivided Family) 
	F - Firm 
	A - Association of Persons (AOP) 
	T - AOP (Trust) 
	B - Body of Individuals (BOI) 
	L - Local Authority 
	J - Artificial Juridical Person 
	G - Govt.*/
	var code= /([C,P,H,F,A,T,B,L,J,G])/;
	var code_chk=textObj.substring(3,4);
	if (textObj!=="")
	{
		if(regpan.test(textObj) == false)
		{
			alert("Invaild PAN Card No.")
			return false; 
		}
		if (code.test(code_chk)==false)
		{
			alert("Invaild PAN Card No.");
			return false;
		}
	}
}