Joakim's public fiddles
I had a case where I needed to check if there is a Swedish social security number or a card number that was entered into a login input before sending. The reason is to delete all unwanted spaces and/or special characters, if I can identify it. If I found a Swedish social security number, I needed to trim it into YYMMDDXXXX, if I identified a card number I needed it to be trimmed to XXXXXXX0303 / XXXXXXX0330. What can identify a social security number is the length of it. If it only consists digits, it should be ten or twelve characters entered in total, not more or less. In this case the card number is always 11 digits, if you remove all other characters and they always ends with "0303" or "0330". This gives me some info to identify card numbers and social security numbers. I am returning false in this function when you submit, just to make sure we do not acually post any values - so you can see the effect. In the real case I return true in all cases, even if not trimmed. If I identify it, I trim the number before sending the data. Other usernames is also used in this form, as "support", etc, that is the reason all get through, even untrimmed usernames.