Add period to Middle Name

Found this javascript in a thread today and helped clean up a messy rule set I had. Thanks

return [Trim(Field("First Name")),Trim(Field("Middle Name")),Trim(Field("Last Name"))].filter(String).join(" ");

My question is can I add to this or do I need to create a new rule and add the rule it to this. I want to take the Middle Name field and if it is 1 character long add a period after it. The trim will take care if it is blank and if it is longer do nothing other than the trim any blank off the end.

Give this a shot:

var mn = Trim(Field("Middle Name"));
return [Trim(Field("First Name")),(mn.length == 1 ? mn + "." : mn),Trim(Field("Last Name"))].filter(String).join(" ");

Thanks.

Worked perfectly.