javascript regex match ^[^#]?

Question

I'm searching a regex in js to match string doesn't start with # the opposite of this function

   String.prototype.parseHashtag = function() {
        return this.match(/[#]+[A-Za-z0-9-_]+/g);
    }

    t="#lorem #ipsum yes no";
    console.log(t.parseHashtag()); // ["#lorem", "#ipsum"]

I found this Regex: Finding strings that doesn't start with X

but the regex doesn't work /([^#]|^)[a-z]/ or maybe I'm tired… I do a replace() but really be curious to understand how to do it in match()!

Here is a js : http://jsfiddle.net/d8HVU/1/

What exactly is your question? Which regex doesn't work? – jfriend00 Mar 02 '12 at 22:11 — jfriend00, Mar 02 '12 at 22:11

score 1 · Answer 1 · edited May 02 '23 at 21:29

1

Non-# character followed by anything:

[^#].*

See it working at http://refiddle.co/1rj

edited May 02 '23 at 21:29

General Grievance

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answered Mar 02 '12 at 22:09

Paul Alexander

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score 1 · Accepted Answer · answered Mar 02 '12 at 22:31

1

I tried this and is working well for Javascript on your sample input. I hope it is also ok for other inputs. Test it well. The other answers did not work out in Javascript.

String.prototype.parseHashtag = function() {
    return this.match(/(\s|^)[^#][\w\d-_]+\b/g);
}

t="#lorem #ipsum yes no";
alert(t.parseHashtag());

answered Mar 02 '12 at 22:31

jdehaan

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+1 probably you are right and this matches the best what OP wants. 2 small things, it will match the whitespace before the word (I think no chance to avoid this, cause Javascript does not support lookbehinds), second no need for `\d` in the charclass, its included in `\w`. – stema Mar 02 '12 at 22:36
Oh, and an important point: escape the dash in the character class or move it to the end it defines a character range (maybe not needed because before is a predefined class, the `\d`). – stema Mar 02 '12 at 22:39
(\s|^) I need to learn regex… ^ is for start or 'not' when it's in [] ? but don't know when is single with | (it's OR ?)… regex is the new sudoku for webdev… – benoît Mar 02 '12 at 23:19
Yes, all right. | is or. Like stema said, maybe you also have to escape the dash, I'm not an expert for JS regexes. I tried to keep as much as possible from your original regex. – jdehaan Mar 02 '12 at 23:29

score 0 · Answer 3 · answered Mar 02 '12 at 22:12

0

If I was trying to match the last hash tag and all chars that follow it, I'd use this regex:

/#[^#]*$/

Working demo: http://jsfiddle.net/jfriend00/nE2bM/

If you're trying to do something different, please clarify exactly what you're asking for.

answered Mar 02 '12 at 22:12

jfriend00

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stema · Answer 4 · 2012-03-02T22:25:44.203

0

You can use a negative lookahead for this

^(?!#).*

See it here on Regexr

This matches each string that does not start with a "#".

OK, I am not sure, do you want to match the start of the string or kind of a "word" that does not start with "#"?

edited Mar 02 '12 at 22:25

answered Mar 02 '12 at 22:13

stema

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javascript regex match ^[^#]?

4 Answers4