Use this Regex for server-side validation also with some slight modifications like so for .NET -- @\w+([-+.']\w+)@\w+([-.]\w+)\.[a-zA-Z0-9]{2,6}(-.{2,6})*;

This is the javascript equivalent that .NET uses in their server-side validators.

get src url from img tag in html

Regex to constrain a text to have at least 2 strings. Compatible with 2nd-3rd-Nth names/surnames.

Grabs all HTML tags

In Ontario, Canada, license classes are combined on the drivers license. This regex will parse out individual classes from the combination.

http://regexone.com/problem/extracting_url_data

Urls ending with a specific domain

This regex represents the httpurl in BNF from rfc1738 (at topic 5). Reference:https://www.ietf.org/rfc/rfc1738.txt

Find all twitter bootstrap buttons with class "btn".

Find all inputs and buttons with class btn.