function str_replace(search, position, replace, subject) {
    var f = search, r = replace, s = subject, p = position;
    var ra = r instanceof Array, sa = s instanceof Array, f = [].concat(f), r = [].concat(r), i = (s = [].concat(s)).length;
    while (j = 0, i--) {
        if (s[i]) {
            while (s[p] = s[p].split(f[j]).join(ra ? r[j] || "" : r[0]), ++j in f){};

        }
    };
    return sa ? s : s[0];
}

//Retorna: 1 = NIF ok, 2 = CIF ok, 3 = NIE ok, -1 = NIF error, -2 = CIF error, -3 = NIE error, 0 = ??? error
function isValidCif(a){

	var temp=a.toUpperCase();
	var cadenadni="TRWAGMYFPDXBNJZSQVHLCKE";
 
	if (temp!==''){
		//si no tiene un formato valido devuelve error
		if ((!/^[A-Z]{1}[0-9]{7}[A-Z0-9]{1}$/.test(temp) && !/^[T]{1}[A-Z0-9]{8}$/.test(temp)) && !/^[0-9]{8}[A-Z]{1}$/.test(temp))
		{
			return 0;
		}
 
		//comprobacion de NIFs estandar
		if (/^[0-9]{8}[A-Z]{1}$/.test(temp))
		{
			posicion = a.substring(8,0) % 23;
			letra = cadenadni.charAt(posicion);
			var letradni=temp.charAt(8);
			if (letra == letradni)
			{
			   	return 1;
			}
			else
			{
				return -1;
			}
		}
 
		//algoritmo para comprobacion de codigos tipo CIF


		suma = parseInt(a.charAt(2))+parseInt(a.charAt(4))+parseInt(a.charAt(6));

		for (i = 1; i < 8; i += 2)
		{
			temp1 = 2 * parseInt(a.charAt(i));
			temp1 += '';
			temp1 = temp1.substring(0,1);
			temp2 = 2 * parseInt(a.charAt(i));
			temp2 += '';
			temp2 = temp2.substring(1,2);
			if (temp2 == '')
			{
				temp2 = '0';
			}
 
			suma += (parseInt(temp1) + parseInt(temp2));
		}
		
		suma += '';
		n = 10 - parseInt(suma.substring(suma.length-1, suma.length));
 		
		//comprobacion de NIFs especiales (se calculan como CIFs)
		if (/^[KLM]{1}/.test(temp))
		{
			if (a.charAt(8) == String.fromCharCode(64 + n))
			{
				return 1;
			}
			else
			{
				return -1;
			}
		}
 
		//comprobacion de CIFs
		if (/^[ABCDEFGHJNPQRSUVW]{1}/.test(temp))
		{
			temp = n + '';
			if (a.charAt(8) == String.fromCharCode(64 + n) || a.charAt(8) == parseInt(temp.substring(temp.length-1, temp.length)))
			{
				return 2;
			}
			else
			{
				return -2;
			}
		}
 
		//comprobacion de NIEs
		//T
		//if (/^[T]{1}/.test(temp))
		if (/^[T]{1}[A-Z0-9]{8}$/.test(temp))
		{
			if (a.charAt(8) == /^[T]{1}[A-Z0-9]{8}$/.test(temp))
			{
				return 3;
			}
			else
			{
				return -3;
			}
		}
 
		//XYZ
		if (/^[XYZ]{1}/.test(temp))
		{
			pos = str_replace(['X', 'Y', 'Z'], 0, ['0','1','2'], temp).substring(0, 8) % 23;
			//pos = str_replace(['X', 'Y', 'Z'], ['0','1','2'], temp).substring(0, 8) % 23;
			if (a.charAt(8) == cadenadni.substring(pos, pos + 1))
			{
				return 3;
			}
			else
			{
				return -3;
			}
		}
	}
 
	return 0;

}