passes freecodecamp's telephone validator

Solves the practice problem from https://www.sitepoint.com/learn-regex/

s matches the character s literally (case sensitive) 1st Capturing Group (\d) \d matches a digit (equivalent to [0-9]) Global pattern flags...

/ \).$ / gm \) matches the character ) literally (case sensitive) ...

Example of how to pull a particular piece of the URL

email address regex

The capture group returns only a number with a dot if it has decimal digits, otherwise it is treated as an integer. 1.1 => 1.1 1\. => 1

Reference: https://stackoverflow.com/a/34669019/369727

about medicine

匹配小数位的整数，或者匹配整数

Given a string, generate random alpha characters of a particular length

Json add q

Mac address is 6 parts of 2 hexadecimal digits separated by a special character "-" so, there are 5 parts of digits followed by the character "-" then, one part without that character.

Setup php source extension regex

Eine Aufgabe die man Lösen muss, wenn man die Lösung kennt.

Phone number regex

Remove bold surrounding italic

this is used for Hdoujin download Hitomi.la Instance

4 "digit" hexadecimal code

got it from here [Regex to match URL, ends up matching URL plus closing brackets when URL is between brackets [duplicate]](https://stackoverflow.com/questions/60476363/regex-to-match-url-ends-up-matching-url-plus-closing-brackets-when-url-is-betwe)