Test and debug regular expressions
g = global, i = case-insensitive, m = multiline, s = dotall
^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$
https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
^\+?1?[-.\s]?\(?([0-9]{3})\)?[-.\s]?([0-9]{3})[-.\s]?([0-9]{4})$
^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$
^\d{4}-\d{2}-\d{2}$
^\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}$