RegEx Notes

Regular Expression
RegEx is a text string used to describe a search pattern (of data like text etc.).

Syntax:   /regex/

Literal character /thewordyourelookingfor/

Flags or modes go after your last /

/regex/ stops when it finds a match
/regex/g looks for match til end of data (doesn't give up)
/regex/i makes regexcase insensitive (otherwise it regex is cs)
/regex/m multiline
/regex/ single line. Allows dot to match newline \n


Metacharacters: \|(){[$.^*+?
These can't be used in literal character search.
If you want to look for any of these 12 char., you have to
escape them by adding a \ in front of them

/(Hey)/   will result in an error. Instead you should write /\(hey\)/

The dot is a wild character. It will match any character except for a newline. To make the dot also match newline you can use the flag/mode single line(s)   /regex/gs

Example

Test string: Kawiesh kawiesh Kawiesh kaw9esh kaw99sh kAw?e$h

/Kawiesh/    Kawiesh ------- ------- ------- ------- -------
/Kawiesh/g   Kawiesh ------- Kawiesh ------- ------- -------
/Kawiesh/gi  Kawiesh kawiesh Kawiesh ------- ------- -------
/Kaw.esh/gi  Kawiesh kawiesh Kawiesh kaw9esh ------- -------

Dot is a place holder for only one character.

Test string:
Kaw
Iesh

/kaw.iesh/gi     no match
/kaw.iesh/gis    match!


....... Other metacharacters.......

\d matches all digits (0-9)
\w matches all letters (lowercase or uppercase), all digits and underscore
\s matches all white spaces (e.g.space, tab, new line)

To match the opposite/inverse match, use capital letters
E.g \D will match every character except digits.