JAVASCRIPT

or in regex

-> You can use "|" operator in between two differebt regex expression 
in php for selection of any one of them

-> Example for Php only
  [a-z]|[0-9] patteren will select either small alphabet or numbers from 
  a string

regex and

(?=.*foo)(?=.*baz)

regex or operator

Grouping Operators (( ... ) or ( ... ))

regex and

/[]/


let bigStr = "big";
let bagStr = "bag";
let bugStr = "bug";
let bogStr = "bog";
let bgRegex = /b[aiu]g/;
bigStr.match(bgRegex);
bagStr.match(bgRegex);
bugStr.match(bgRegex);
bogStr.match(bgRegex);