RegEx to match a valid JavaScript namespace

Question

What would be the regular expression to match a correct any-depth JavaScript namespace?

Valid Entries

a
a.b
$a._b.$$c.__d
a_$09.b_$09.c_$09

So basically, JavaScript open-name variables joined by dot, and each separate name can contain a-z, A-Z, _, $ and 0-9, but cannot start with 0-9.

Invalid Entries

1a - cannot start with a digit
abc.1a - a sub-name cannot start with a digit also
.a - cannot have a leading dot
a. - cannot end with a dot

I have tried this one: ^([a-z$_][a-z$_0-9]*\.?)*[^\.]$, which while bans the trailing ., allows any extra symbols in the end, such as ,, which is invalid.

@Sphinx Just tried, it works, though I prefer shorter: /^[a-z][0-9a-z\$\_]*(\.[a-z][0-9a-z\$\_]*)*$/i :) — vitaly-t
– vitaly-t, Commented Aug 2, 2018 at 23:42
@Sphinx Ops, just found a problem - it doesn't allow leading $ or _, which it should, just like for any open-name JavaScript variable ;) — vitaly-t
– vitaly-t, Commented Aug 2, 2018 at 23:44
^[_$a-zA-Z][\w$]*(\.[a-zA-Z][$\w]*)*$ is a simplified version of @Sphinx's regex — emsimpson92
– emsimpson92, Commented Aug 2, 2018 at 23:46

Sphinx · Accepted Answer · 2018-08-03 00:09:34Z

1

Uses ^[a-zA-Z\$\_][0-9a-zA-Z\$\_]*(\.[a-zA-Z\$\_][0-9a-zA-Z\$\_]*)*$

because \w matches any word character (equal to [a-zA-Z0-9_]),

so as @emsimpson92 said, you can have one simplified version:

^[a-zA-Z\$\_][\$\w]*(\.[a-zA-Z\$\_][\$\w]*)*$

for the shortest version so far as @vitaly-t commented (removed unnecessary escaping), it will be:

/^[a-z$_][$\w]*(\.[a-z$_][$\w]*)*$/i

Regex Online

edited Aug 3, 2018 at 0:09

answered Aug 2, 2018 at 23:47

Sphinx

10.7k2 gold badges35 silver badges50 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

vitaly-t Over a year ago

I think this one is then the most elegant: /^[a-z\$\_][\$\w]*(\.[a-z\$\_][\$\w]*)*$/i.

vitaly-t Over a year ago

Actually, you do a lot of escaping that's not needed. So the ultimate shortest version is: /^[a-z$_][$\w]*(\.[a-z$_][$\w]*)*$/i, if you want to update the answer ;)

Sphinx Over a year ago

@vitaly-t, Hah, thanks for the suggestions. it is my bad habit, add escaping for all special characters...

Collectives™ on Stack Overflow

RegEx to match a valid JavaScript namespace

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related