Scriptlet: Format Phone Value

//returns xxx-xxx-xxxx format
function ConvertPhone(phone) { 
var formatted = phone.replace(/[^0-9]+/g, ''); 
if (formatted.length == 10){
formatted = formatted.replace(/^[2-9]\d{2}-\d{3}-\d{4}$, '$1-$2-$3'/); 
} 
else {
formatted = respondent.phone;
}
return formatted; 
}