Improve JS Regex pattern for name validation

Question

I am trying to create a regex pattern for name validation. Application name must have the following:

Lowercase alphanumeric characters can be specified
Name must start with an alphabetic character and can end with alphanumeric character
Hyphen '-' is allowed but not as the first or last character e.g abc123, abc, abcd-1232

This is what I got [^\[a-z\]+(\[a-z0-9\-\])*\[a-z0-9\]$][1] it doesn't work perfectly. The validation fails if you enter a single character in the field. How can I improve this pattern? Thank you in advance.

Tim Biegeleisen · Accepted Answer · 2022-08-26 08:52:41Z

1

You may use the following pattern:

^[a-z](?:[a-z0-9-]*[a-z0-9])?$

Explanation:

^[a-z] starts with lowercase alpha
(?: turn off capture group
- [a-z0-9-]* zero or more alphanumeric OR dash
- [a-z0-9] mandatory end in alphanumeric only, if length > 1
)? make this group optional
$ end of input

answered Aug 26, 2022 at 8:52

Tim Biegeleisen

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The fourth bird · Accepted Answer · 2022-08-26 09:02:04Z

0

You are using a negated character class [^ that matches 1 character, not being any of the specified characters in the character class.

That is followed by another character class [1] which can only match 1, so the pattern matches 2 characters, like for example #1

In your examples you seem to have only a single hyphen, so if there can not be consecutive hyphens --

^[a-z][a-z0-9]*(?:-[a-z0-9]+)*$

Explanation

^ Start of string
[a-z] Match a single char a-z
[a-z0-9]* Optionally repeat any of a-z or 0-9
(?:-[a-z0-9]+)* Optionally repeat matching - followed by at least 1 or a-z or 0-9 (So there can not be a hyphen at the end)
$ End of string

Regex demo

answered Aug 26, 2022 at 9:02

The fourth bird

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