Regex matches parts of a string, but not whole string

Question

This is the regex I\'m using to validate a string that can contain lowercase and uppercase letters, numbers and dash:

/([a-zA-Z0-9-])+$/

It has

Answer 1

I would say you need /^([a-zA-Z0-9-])+$/. You want to match the whole string, not just a part, but you're missing the mark for the beginning of the string ^.

^ and $ say between the beginning and the end of the string and ([a-zA-Z0-9-])+ says there can be one or more characters a-zA-Z0-9-.

Your regexp matches everything which contains one or more characters a-zA-Z0-9- before the end of the string no matter what's before.

You can test your regular expression on regex101.com (very good online tool for regular expression testing with explanation, reference etc.).