Q: Safari-Alert ?scam?

I also received this so-called safari message that leads me to call this number 'that's not Apple" what I had did to rid this was NOT press ok ! I exited out of the page and then went into my setting I clicked safari and to clear browsing history this then got rid of the message.

Can one ever enable JavaScript again?

Certainly.

Should you be weary about bank info and credit card info after you turn it back on?

No. There is really nothing else to worry about.