JAVASCRIPT

regex any character

/(.*)/

regex any letter

[a-zA-Z] //all letters
[a-z] //only lowercase letters
[A-Z] //only uppercase letters

regex any character

/(.*?)/

regex match any character

// This will match all characters except a new line
.{3,}

regex any character

. = any char except newline
. = the actual dot character
.? = .{0,1} = match any char except newline zero or one times
.* = .{0,} = match any char except newline zero or more times
.+ = .{1,} = match any char except newline one or more times