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
– jfriend00

2012-03-02 22:11:08 +00:00
Commented Mar 2, 2012 at 22:11 — jfriend00
– jfriend00, Commented Mar 2, 2012 at 22:11

jdehaan · Accepted Answer · 2012-03-02 22:31:06Z

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 2, 2012 at 22:31

jdehaan

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4 Comments

stema Over a year ago

+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 Over a year ago

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).

benoît Over a year ago

(\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…

jdehaan Over a year ago

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.

General Grievance · Accepted Answer · 2023-05-02 21:29:30Z

1

Non-# character followed by anything:

[^#].*

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

edited May 2, 2023 at 21:29

General Grievance

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answered Mar 2, 2012 at 22:09

Paul Alexander

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Comments

jfriend00 · Accepted Answer · 2012-03-02 22:12:53Z

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 2, 2012 at 22:12

jfriend00

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Comments

stema · Accepted Answer · 2012-03-02 22:25:44Z

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 2, 2012 at 22:25

answered Mar 2, 2012 at 22:13

stema

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