function pesel_check(el) {
var pesel_waga = '13791379131';
var pesel_suma = 0;
if (el.value.length = 11) {
for (a = 0; a <= 10; a++)
pesel_suma = pesel_suma + (el.value.substr(a, 1) * pesel_waga.substr(a, 1));
pesel_suma_str = pesel_suma.toString();
if (pesel_suma_str.substr(-1, 1) == '0') {
return true;
} else {
el.errors.push("Nieprawidłowy numer PESEL");
return false;
}
}
}