javascript regex - global replace issue

Question

I'm getting content from a textarea (which besides simple text may include html markup), and try to parse it and replace all occurences of "[File:#xx#]" with a string contained in an array. So, lets say the contents of the textarea is in var html.
I do the following:

html = html.replace(/\[File:#(.*)#\]/g, 
                    function($0, $1){ return furls[$1]; });

everything works fine when the contents the text area are like this:

<img src="[File:#111#]" alt="image1" />
<img src="[File:#222#]" />

but when there is no line break between 2 elements witch have attribute with [File:#xx#] value, then the problem appears.
So, given this as the textarea's value:

<img src="[File:#111#]" alt="image1" /><img src="[File:#222#]" />

seems like it matces the first img's [File:#111# but closes it not with the first bracket, rathen than the second one's. so, what gets replaced is all this:
#]" alt="image1" /><img src="[File:#222

What is wrong with my regular expression? How can i prevent this look-ahead from happening and stop at the first closing bracket?

Thanks in advance.

Bogdan Emil Mariesan · Accepted Answer · 2012-03-30 14:25:56Z

1

Well the correct regex for your case would be:

/[File:#[\w]+#]/g

Why is this the case?

Because in your regex:

The . Matches any character, except for line breaks if dotall is false.

The * Matches 0 or more of the preceeding token. This is a greedy match, and will match as many characters as possible before satisfying the next token.

And in the regex i've provided:

The \w Matches any word character (alphanumeric & underscore).

answered Mar 30, 2012 at 14:25

Bogdan Emil Mariesan

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2 Comments

CdB Over a year ago

Thanks a lot Bogdan for replying. It's enough for what i currently need, but What if i need to support any character, like [File:#http://test.com/file1?a=1&b=2#]

Bogdan Emil Mariesan Over a year ago

If you want to add other characters in your search you could have a regex like: /[File:#[\w=&?/.]+#]/g This will match the example you provided in the comment

Russell G · Accepted Answer · 2012-03-30 14:26:00Z

1

The problem is that it's grabbing everything from the first # sign to the last one, because you're using (.*), which matches all characters. Try this instead, which limits the matched part to just numeric digits:

html = html.replace(/\[File:#([0-9]*)#\]/g, 
                function($0, $1){ return furls[$1]; });

answered Mar 30, 2012 at 14:26

Russell G

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1 Comment

CdB Over a year ago

Thanks for replying russell. File ids may contain letters as well, so i picked Bogdan's answer. Thanks again for bothering :)

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