cpf.js

var validate_cpf = function(value) {
  var cpf = value.replace('-', '').replace('.', '');
	
	while(cpf.length < 11) cpf = "0"+ cpf;
	
	var expReg = /^0+$|^1+$|^2+$|^3+$|^4+$|^5+$|^6+$|^7+$|^8+$|^9+$/,
		a = [], b = new Number, 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;
};