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I need some help converting this PHP regular expression to a Javascript one though I am not very familiar to regular expressions:

$regex = "((https?|ftp)\:\/\/)?"; // SCHEME
$regex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass
$regex .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP
$regex .= "(\:[0-9]{2,5})?"; // Port
$regex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path
$regex .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query
$regex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor
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it should be the same. have you tried it? –  Karoly Horvath Jun 29 '13 at 15:33
 
Possible duplicate of stackoverflow.com/questions/9309349/… –  x_vi_r Jun 29 '13 at 15:34
1  
@x_vi_r: that's definitely not a duplicate. –  Karoly Horvath Jun 29 '13 at 15:35
 
@KarolyHorvath Why not ? –  x_vi_r Jun 29 '13 at 15:36
2  
sigh why yes? just because there are similar keywords in the question it doesn't mean it covers it. –  Karoly Horvath Jun 29 '13 at 15:36
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closed as off-topic by Karoly Horvath, andrewsi, JDB, HamZa, Alez Jul 17 '13 at 14:50

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist" – JDB, HamZa
If this question can be reworded to fit the rules in the help center, please edit the question.

1 Answer

up vote 3 down vote accepted

While the others are correct, that using some other means to parse the function would be easier, here is how you can convert the regex.

The regex contains no advanced constructs which are not available in JavaScript or have a different meaning. Hence, you can simply use the same expression in a regex literal:

var r = /((https?|ftp)\:\/\/)?([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?([a-z0-9-.]*)\.([a-z]{2,3})(\:[0-9]{2,5})?(\/([a-z0-9+\$_-]\.?)+)*\/?(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?(#[a-z_.-][a-z0-9+\$_.-]*)?/;

Now regex literals don't support concatenation, and neither does JS have the x modifier which would allow you to split the expression of multiple lines. So if you want to keep the pattern in multiple parts, to comment it, you'll have to concatenate a string again and pass that string to the RegExp constructor. The catch here is that backslashes need to be doubled, because JavaScripts string compilation will swallow up each unescaped backslash (so you need to escape the backslashes for them to reach the regex engine):

var rString = "((https?|ftp)\\:\\/\\/)?"; // SCHEME
rString += "([a-z0-9+!*(),;?&=\\$_.-]+(\\:[a-z0-9+!*(),;?&=\\$_.-]+)?@)?"; // User and Pass
rString += "([a-z0-9-.]*)\\.([a-z]{2,3})"; // Host or IP
rString += "(\\:[0-9]{2,5})?"; // Port
rString += "(\\/([a-z0-9+\\$_-]\\.?)+)*\\/?"; // Path
rString += "(\\?[a-z+&\\$_.-][a-z0-9;:@&%=+\\/\\$_.-]*)?"; // GET Query
rString += "(#[a-z_.-][a-z0-9+\\$_.-]*)?"; // Anchor
var r = new RegExp(rString);

In any case, r can now be used with your favourite matching function (match on a string, or test or exec on r).

share|improve this answer
 
So useful. Thanks man! –  Myownway Jun 29 '13 at 23:59
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