Regular Expressions 101

^start of line

Character Class[a-z]+

+matches at least one character from the set below:

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

Non-Capturing Group(?:_[a-z]+)*

*repeats the group contents below any number of times:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

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

$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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^[a-z]+(?:_[a-z]+)*$

Test String
New

welcome_to_snake_case

PASS :
snake_case
cellule
sous_cellule
a
a_a
all_good

FAIL :
/^[a-z]+(\_[a-z]+)*$/gm
camelCase
PascalCase
kebab-case
UPPERCASE
big_sNAKe_case
snake_digita1ised_case
one_is_there^
_
___
no_trailing_dash_
_actually_neither_way
_norboth_
no_space 
no_other_special-char
all_good?yes

Regular Expression

Test StringNew

Test String
New