Rules question

hello

Im new to FusionPro and i had a quick question

I'm not very knowledgeable in javascript but I'm reaching out for a bit of help with a issue I'm having

Here is an example of the text I'm using

"….call me at «Phone_number» ext. «FA_ext»"

The ext. is optional.

If a user doesn't have an extension is there a rule that can be used to delete "ext. «FA_ext»" and just put the number there?

Any help or direction would be greatly appreciated

Thank you

Drew

if (!Field("FA_ext"))
   return "";
//else
return " ext. " + Field("FA_ext");