Phone number formatting using javascript

Hi Thom,
I look forward to seeing you at this year's PDF conference! Question: I have a javascript that I muddled through (with others' help) to force the formatting of a phone number. Currently, I have a custom format script for the field that looks like this:
 
// RegExp input (999-999-9999) for format
var re = /^(\d{3})[-](\d{3})[-](\d{4})$/
if(re.test(event.value) == true)
{
event.value = RegExp.$1 + "." + RegExp.$2 + "." + RegExp.$3;
}
 
and a custom keystroke script that looks like this:
 
// RegExp input (999-999-9999) for format
var re = /^(\d{3})[-](\d{3})[-](\d{4})$/
if(re.test(event.value) == true)
{
event.value = RegExp.$1 + "." + RegExp.$2 + "." + RegExp.$3;
}
 
It is currently taking input of a number in the format of 555-555-5555 and converts it to 555.555.5555. I need to add the functionality to the script so that it will take input of 5555555555 and format it in the same way. I'm not sure where to go about modifying my script to make this happen. Can you help? Thanks!