Create
A regular expression is a type of object. It can be either constructed with the RegExp constructor or written as a literal value by enclosing a pattern in forward slash (/) characters.
let re1 = new RegExp("abc");
let re2 = /abc/;
Shortcuts
A number of common character groups have their own built-in shortcuts.
( e.g. \d 相当于 [0-9] / [0123456789] )
\d Any digit character
\w An alphanumeric character (“word character”)
\s Any whitespace character (space, tab, newline, and similar)
\D A character that is not a digit
\W A nonalphanumeric character
\S A nonwhitespace character
. Any character except for newline
