Here's an example of a regex to validate us phone numbers

https://regexper.com/#%2F%5E(1%5Cs%3F)%3F(%5B0-9%5D%7B3%7D%7...

From

https://www.freecodecamp.org/challenges/validate-us-telephon...

I found these 11 videos most helpful when learning regex from codecourse

https://www.youtube.com/watch?v=GVZOJ1rEnUg&index=1&list=PLf...