Rather than name only a single character, you can include a pattern in a regular expression that matches any of a set of characters.
A set of characters can be given as a simple list inside square brackets, e.g.¬†
/[aeiou]/¬†will match any single lowercase vowel. For letter or number ranges you may also use only the first and last letter of a range, with a dash in the middle, e.g.¬†
/[A-Ma-m]/¬†will match any lowercase or uppercase in the first half of the alphabet.
Many regular expression tools also provide escape-style shortcuts to the most commonly used character class, such as¬†
\s¬†for a whitespace character and¬†
\d¬†for a digit. You could always define these character classes with square brackets, but the shortcuts can make regular expressions more compact and more readable.