I accept for various reasons you may be able to or see it sensible to help however I thought there was no problem in asking.
I am getting confused what approach to take with this project. Learn Regular Expressions by Building a Spam Filter: Step 36 | freeCodeCamp.org. I try to work out whether using just a single regular expression is the way to go to validate a phone number is valid like ( Learn Regular Expressions by Building a Spam Filter: Step 36 | freeCodeCamp.org) or whether to do it another way. Such as by dealing with the county code separately, not using regular expressions at all or somewhere in the middle of these two approaches (the other ones in the sentence). To be clear I know to deal with blank input separately.
I think you are asking if you can use one regex or multiple ones?
The answer is, use whatever you can that will work.
(some people use one, some people use multiple)
What I am asking includes that but I appear from what you are saying using one is not making things harder for yourself than necessary, so I will continue try this way.
your title does not match what you are asking, maybe you want to update that
it is not clear which project you are asking about, you talk about validating numbers but your links do not match that
i cannot tell you which way will be harder for you. If you go down one path and find yourself looking at another route that seems easier, feel free to try it. There are multiple ways to reach a solution.