Simple JS function to validate CPF numbers

is_cpf.js

// a simple js function to validate CPF numbers
function iscpf(c){
	if(!isNaN(c))
		c = ""+c;
	var re = /^(\d{1})(\d{1})(\d{1})(\d{1})(\d{1})(\d{1})(\d{1})(\d{1})\d{3}$/.exec(c);
	if(!re)
		return false;
	var i = 2, j = 0, k = 0, g = re[1];
	for(;i<re.length;i++)
		if(re[i]!=g)
			break;
	if(i==9)
		return false;
	c = c.split("");
	for(i=0;i<9;i++)
		j+=c[i]*(10-i);
	for(i=0;i<9;i++)
		k+=c[i]*(11-i);
	j = 11-(j%11);
	j = (j<10)?j : 0;
	k += j*2;
	k = 11-(k%11);
	k = (k<10)?k : 0;
	return (j==c[9] && k==c[10]);
}