This regex will identify all html start and end tags.

From 1970 to 2015 Replace: (\d{4})$ for (19[7-9]\d|200-1)$

Find and extract email domain. Ex: test@example.pt -> extract 'example.pt'

Find " and ' quoted strings and "orphaned"/single words in a string

checks for valid PAN card for Indian users.

Extract resource location, name and query parameters from a URL (JavaScript version)

http://stackoverflow.com/q/25778420/2072035

matches full if condition statment eg: if(condition){ ... } else if(condition){ ... }else{...

A-Za-z\x{0600}-\x{06FF}\x{1000}-\x{1021}_-*

used to parse timezone in the format -08:00 or +05:30

main symbols and comments are supported

global modifier

IOS3166 Country Code Identification REGEX

Besides leap year handling, this takes care of date validation in the yy-mm-dd format.