checkInternationalPhone,stripCharsInBag,isInteger JS

function isInteger(s)
{ var i;
for (i = 0; i < s.length; i++)
{
var c = s.charAt(i);
if (((c < "0") (c > "9"))) return false;
}
return true;
}
function stripCharsInBag(s, bag)
{ var i;
var returnString = "";
for (i = 0; i < s.length; i++)
{
var c = s.charAt(i);
if (bag.indexOf(c) == -1)
returnString += c;
}
return returnString;
}
function checkInternationalPhone(strPhone)
{
var phoneNumberDelimiters = "()- ";
var validWorldPhoneChars = phoneNumberDelimiters + "+";
s=stripCharsInBag(strPhone,validWorldPhoneChars);
return (isInteger(s) && s.length >= 10);
}