Regex: Only allow certain format within string

I am using regex to validate input within a Google form, the input value should only contain the following formats . For example should work but or should not. I have tried to use the following regex

But this does not limit to the following input

>Solution :

You could shorten it to an alternation, and not that SSDC66765 has 5 digits so the quantifier can be {3,5} instead (or adjust to your needs)

^(?:SS(?:FW|DC)?|[HT]R)\d{3,5}$

The pattern matches:

• ^ Start of string
• (?: Non capture group
  • SS(?:FW|DC)? Match either SS SSFW or SSDC
  • | Or
  • [HT]R Match either HR or TR
• ) Close non capture group
• \d{3,5} Match 3 – 5 digits
• $ End of string

Regex demo