Input type validation using Regular Expression

Three letter country code validation

input type="text" name="country_code" pattern="[A-Za-z]{3}" title="Three letter country code"

Email address validation

^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$

Date validation[yyyy-mm-dd]

^(19|20)\d\d[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$

Regular Expression	Description
[abc]	Any character between the brackets
[^abc]	Any character not between the brackets
[0-9]	Any digit between the brackets
[^0-9]	Any digit not between the brackets
(x|y)	Any of the alternatives specified
[a-z]	Any character from lowercase a to z
[A-Z]	Any character from lowercase A to Z
[^a-zA-Z]	Any string not containing any of the characters ranging from a-z and A-Z.
^.{2}$	It matches any string containing exactly two characters.