Javascript regular expression for a subject field

[JnrJnr]

Hi people, I have this regex?

/^[a-zA-Z0-9]+[\s]*[a-zA-Z0-9]+$/

I want the field to start with alphanumeric and allow single white spaces (or no white spaces) zero or more times and zero or more times in the sentence and then end with alphanumeric.
For example:
1. Hello John123
2. Hello John123 (with maybe 3 spaces between hello and John 123)
3. Hello John123 how are you

Help would be appreciated!

[Dormilich]

you can use parentheses (groups) to get that repetition.

// simplified example
/^\w(?:\s?\w)+$/

[JnrJnr]

Thanks it works for me but could you please explain how the parentheses or groups work? Im still new to regex

[Dormilich]

well, it’s just that, a group. nothing complicated there.

[JnrJnr]

Anything desired to know that needs understanding is complicated till it is known.
Thanks again

[Dormilich]

some things are so simple, that it’s hard to explain in a simpler way. other than that I can only refer to RegExp tutorials like this one.

[JnrJnr]

There are many tutorials and quick starts on regular expressions but I just did not know how the parentheses or groups work. A bit better link would be this http://www.regular-expressions.info/brackets.html
tanx