This presentation actually demonstrates some of the famous regex for validating e-mail, URL, IP Address, username, Password, HTML tag etc..

1. JavaScript RegEx -
Examples

2. Matching a Username
 the input name should only contains a-z, 0-9, and -,_
 The input name should be minimum of 3 letters and maximum of 13.

3. Matching a Username

4. /^[a-z0-9_-]{3,16}$/
 Description:
 We begin by telling the parser to find the beginning of the string (^),
followed by any lowercase letter (a-z), number (0-9), an underscore, or
a hyphen. Next, {3,16} makes sure that are at least 3 of those
characters, but no more than 16. Finally, we want the end of the string
($).
 String that matches:
 my-us3r_n4m3
 String that doesn't match:
 th1s1s-wayt00_l0ngt0beausername (too long)

5. Matching a Password

6. Matching a Password

7. Matching a Hex Value

8. Matching a Hex Value

9. Matching a Slug

10. Matching a Slug

11. Matching an Email

12. Matching an Email

13. Matching a URL

14. Matching a URL

15. Matching an IP Address

16. Matching an IP Address

17. Matching an HTML Tag