Pete Freitag Pete Freitag

Let the computer do the formatting

Published on December 22, 2005
By Pete Freitag

Brian Crescimanno recently published a form usability checklist on A List Apart. It's a great article that hits home some of my form pet peeves.

One of the points he makes is to let the computer do the formatting:

Few things confuse users as often as requiring that users provide information in a specific format....

Be reasonable; are we so afraid of regular expressions that we can't strip extraneous characters from a single input field? Let the users type their telephone numbers in whatever they please. We can use a little quick programming to filter out what we don?t need.

It is pretty easy to write a regular expression that takes out anything but numbers, you would do it like this in CFML:

<cfset = "(800) 555-1212">
<cfset cleanPhone = ReReplace(, "[^0-9]", "", "ALL")>

Now your left with a variable cleanPhone that has just the phone number digits. So now you need to format the phone number yourself, this can also be done easily with the help of the Left, Right, and Mid functions in ColdFusion:

<cfset areaCode = Left(cleanPhone, 3)>
<cfset firstThree = Mid(cleanPhone, 4,3)>
<cfset lastFour = Right(cleanPhone, 4)>
<cfoutput>(#areaCode#) #firstThree#-#lastFour#</cfoutput>

This example however does make the assumption that the phone number is a US phone number. Things can get a bit more tricky when you add international phone numbers, and extensions into the mix.

validation form usability phone formatting regex

Let the computer do the formatting was first published on December 22, 2005.

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I wrote this big long script for parsing / normalizing any phone number (local, North American, international, etc.) It was a pain, let me tell you. I may get around to posting that code for people to pick apart on my site (
by Mike DeWolfe on 12/22/2005 at 3:04:02 PM UTC
Here's a slight improvement -

<cfset cleanPhone1 = ReReplace(form.office_phone, "[[:space:]]", "", "ALL")>
<cfset cleanPhone1 = ReReplace(form.office_phone, "[[:punct:]]", "", "ALL")>
<cfset cleanPhone1 = ReReplace(form.office_phone, "[^0-9]", "", "ALL")>

<cfset areaCode1 = Left(cleanPhone1, 3)>
<cfset firstThree1 = Mid(cleanPhone1, 4,3)>
<cfset lastFour1 = Right(cleanPhone1, 4)>
<cfset finalphone1 = areacode1&'-'&firstThree1&'-'&lastFour1>
by Steve Dan on 05/14/2007 at 2:47:14 PM UTC
I made this function from your snippet that works with both 7 and 10 digit phone numbers

<cffunction name="phoneFormat" returnformat="plain" access="public">
<cfargument name="phone" required="Yes" type="string">
<cfset cleanPhone = ReReplace(, "[^0-9]", "", "ALL")>
<cfif len(cleanPhone) eq 10>
<cfset areaCode = Left(cleanPhone, 3)>
<cfset firstThree = Mid(cleanPhone, 4,3)>
<cfset lastFour = Right(cleanPhone, 4)>
<cfset formattedPhone="(#areaCode#) #firstThree#-#lastFour#">
<cfelseif len(cleanPhone) eq 7>
<cfset firstThree = Left(cleanPhone, 3)>
<cfset lastFour = Right(cleanPhone, 4)>
<cfset formattedPhone="#firstThree#-#lastFour#">
<cfreturn formattedPhone>
by Ernest Breau on 11/21/2008 at 6:30:26 AM UTC