Question

I need some help in evaluating a regular expression in some code.I am trying to evaluate the regular expression

/^\s*(\*|[\w\-]+)(?:\b|$)?/i

I think I figured the following:

^ – Beginning of character

\s* – zero or more occurrences of white space

(\*|[\w\-]+) – I understand the \w standards for word but I am not sure what \* and the or | is evaluating to and the + specifies one more more occurrence of the preceding pattern.

(?:\b|$)? – I need help in understanding this and the expression as a whole.

i – Ignore case

Can some help me understand what (?:\b|$)? is evaluating for and the expression as whole? Any help would be appreciated.

Answer 1

/                # Start regex delimiter.
^                # Anchor to start of string.
\s*              # Match 0 or more whitespace (\s) characters.
(\*|[\w\-]+)     # Alternation between a literal `*` and one or more word
                 # characters (\w) or a dash (needlessly escaped). Store in
                 # capturing group 1.
(?:\b|$)?        # Create a non capturing alternation between a word boundary
                 # or the end of the string. This entire alternation is 
                 # optional.
/                # End regex delimiter.
i                # Make the regex case insensitive. Needless here as there is 
                 # no literal alphabetical characters used.