Regular Expressions 101

Explanation
Pro

^start of line

Negative Lookahead(?![0-9-]+$)

Character Class[0-9-]+

+matches at least one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

$end of line

Non-Capturing Group(?:[a-z]{2,}-?|[0-9]-?)+

+repeats the group contents below at least once:

1st Alternative[a-z]{2,}-?

Character Class[a-z]{2,}

{2,}matches at least 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

2nd Alternative[0-9]-?

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

Negative Lookbehind(?<!-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

^(?![0-9-]+$)(?:[a-z]{2,}-?|[0-9]-?)+(?<!-)$

New


(NULL STRING ABOVE)
555
 5
 5-yes
 this-slug
--bad-slug
-bad-slug
bad--slug
bad-slug-
bad-slug--
b
a
d
b-a-d
go-od-2-ba-d
1-b
good-b4d
1-1b
1-1
1-2-33
go-od-to-go
1-good-slug
10-good-slugs
best-slug-ever
good-slug
slug-123
good
good-1