CODEWITHSUNDEEP
javascriptregexecmascript-6regex-groupregex-negation
Hedi Herdiana
Hedi Herdiana

Reputation: 101

Matching image path inside javascript using javascript regex

I need a regex to scan JS files for any image paths it finds.

These paths would generally be nested as follows:

$img1 = "foo/bar.png";
$img2 = 'foo/bar.jpg';
$img3 = "{'myimg':'foo/bar.png'}";

I need a regex which will be able to pick up the whole image path inside the quotes, but sometimes nested inside a json string, or otherwise encoded... essentially, matching a whole image path by detecting just the existence of the extension (jpg|png|gif).

I have found a regex that works well in php, I need one that works with javascript.

$pattern = '~/?+(?>[^"\'/]++/)+[^"\'\s]+?\.(?>(?>pn|jpe?)g|gif)\b~';

How the form of regex pattern in javascript?

Upvotes: 1

Views: 857

Answers (2)

The fourth bird
The fourth bird

Reputation: 163632

Possessive quantifiers ++ and atomic groups (?> are not supported in Javascript.

The updated pattern could look like this:

\/?(?:[^"'/]+\/)+[^"'\s]+?\.(?:(?:pn|jpe?)g|gif)\b

But to get those matches and if // in the path is also ok, you can exclude matching the quotes using a negated character class [^"']* only

Note to escape the \/ as the regex delimiters in Javscript are / and that you don't have to escape the ' and " in the character class.

The shorter version could look like

[^"']+\.(?:(?:pn|jpe?)g|gif)\b
  • [^"']+ Match any char except ' or " 1+ times
  • \. Match a dot
  • (?: Non capture group
    • (?:pn|jpe?)g Match either png jpg or jpeg
    • | Or
    • gif Match literally
  • )\b Close non capture group followed by a word boundary

Regex demo

const regex = /[^"']+\.(?:(?:pn|jpe?)g|gif)\b/;
[
  "foo/bar.png",
  "foo/bar.jpg",
  "{'myimg':'foo/bar.png'}"
].forEach(s => console.log(s.match(regex)[0]));

Upvotes: 2

Ryszard Czech
Ryszard Czech

Reputation: 18641

I'd use

string.match(/[^"'<>]+\.(?:png|jpe?g|gif)\b/gi)

See proof. Note: g - all occurrences, i - case insensitive, <> added to the expression to limit matching up to a tag.

Explanation

--------------------------------------------------------------------------------
  [^"'<>]+                 any character except: '"', ''', '<', '>'
                           (1 or more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  \.                       '.'
--------------------------------------------------------------------------------
  (?:                      group, but do not capture:
--------------------------------------------------------------------------------
    png                      'png'
--------------------------------------------------------------------------------
   |                        OR
--------------------------------------------------------------------------------
    jp                       'jp'
--------------------------------------------------------------------------------
    e?                       'e' (optional (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    g                        'g'
--------------------------------------------------------------------------------
   |                        OR
--------------------------------------------------------------------------------
    gif                      'gif'
--------------------------------------------------------------------------------
  )                        end of grouping
--------------------------------------------------------------------------------
  \b                       the boundary between a word char (\w) and
                           something that is not a word char

Upvotes: 2

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