CPF validation for jQuery Validate

jquery.validate.cpf.js

jQuery.validator.addMethod("cpf", function(value, element) {
  value = value.replace('.','');
	value = value.replace('.','');
	cpf = value.replace('-','');
	while(cpf.length < 11) cpf = "0" + cpf;
	var expReg = /^0+$|^1+$|^2+$|^3+$|^4+$|^5+$|^6+$|^7+$|^8+$|^9+$/;
	var a = [];
	var b = new Number;
	var c = 11;
	for (i=0; i<11; i++){
		a[i] = cpf.charAt(i);
		if (i < 9) b += (a[i] * --c);
	}
	if ((x = b % 11) < 2) { a[9] = 0 } else { a[9] = 11-x }
	b = 0;
	c = 11;
	for (y=0; y<10; y++) b += (a[y] * c--);
	if ((x = b % 11) < 2) { a[10] = 0; } else { a[10] = 11-x; }
	if ((cpf.charAt(9) != a[9]) || (cpf.charAt(10) != a[10]) || cpf.match(expReg)) return false;
	return true;
}, "Informe um CPF v&aacute;lido.");