RegExp for BBCode tags javascript

Question

I have this RegExp, and i dont know what's wrong with it

tag = new RegExp('(\\['+tag+'=("|'|)(.*?)\1\\])((?:.|\\r?\\n)*?)\\[/'+tag+']','g');

The bbcode tags can have double quotation marks, single quotation marks or no quotation marks.

[tag="teste"]123[/tag]
[tag='teste']123[/tag]
[tag=teste]123[/tag]

Desired output in captures: teste and 123

To match the optional quotation marks, it should be ("|'|), (["|\']*) or ("|\'?)?

Just some syntax errors: new RegExp('(\\['+tag+'=(["\']|)(.*?)\\1\\])([\\s\\S]*?)\\[/'+tag+']','g');. I also change ((?:.|\\r?\\n)*?) to ([\s\S]*?), since it seems to be your intention — nhahtdh
– nhahtdh, Commented Sep 4, 2015 at 3:02
if you don't know what's wrong with it, then how do you know it's wrong? — CrayonViolent
– CrayonViolent, Commented Sep 4, 2015 at 3:02
@Eduardo I found it difficult to read, so I expanded based on the info you provided in comments / answer — Mariano
– Mariano, Commented Sep 7, 2015 at 8:37

Mariano · Accepted Answer · 2015-09-07 08:58:42Z

1

Whats wrong with the string

First, let's correct the syntax in your string

You need to define the var tag

tag = 'tag';
result = new RegExp( <...>  );

You have unballanced quotes in '("|'|) <...> ', that needs to be escaped as ("|\'|)
Also, escape \1 as \\1

so now we have the expression '(\\['+tag+'=("|\'|)(.*?)\\1\\])((?:.|\\r?\\n)*?)\\[/'+tag+']' with the value:

(\[tag=("|'|)(.*?)\1\])((?:.|\r?\n)*?)\[/tag]

What's wrong with the RegEx

Only one thing really, in ("|\'|)(.*?)\\1 you're using \1 to match the same quotation mark as the one used as opening. However, the 1 refers to the first capturing group (the first parenthesis from left to right), but ("|'|) is actually the second set of parenthesis, the second group. All you need to do is change it to \2.

(\[tag=("|'|)(.*?)\2\])((?:.|\r?\n)*?)\[/tag]

That's it!

Let's add some final suggestions

Instead of .*? I would use [^\]]+ (any characters except "]")
Use the i modifier (case-insensitive match, for "[tag]...[/TaG]")
("|'|) is the same as ("|'?)
Instead of (?:.|\r?\n)*? I would use [\s\S]*? as @nhahtdh suggested

Code:

tag = 'tag';
result = new RegExp('(\\['+tag+'=("|\'?)([^\\]]+)\\2\\])([\\s\\S]*?)\\[/'+tag+']','gi');

Alternative: [EDIT: from info added in comments]

result = new RegExp('\\['+tag+'(?:=("|\'?)([^\\]]+)\\1)?\\]([\\s\\S]*?)\\[/'+tag+']', 'gi');

As for your second question: Although both (["|\']*) and ("|\'?) will match, the latter is the correct way for what you're trying to match. The * looks for 0 to infinite repetitions, and the | is interpreted as literal in a character class. Instead, ("|\'?) matches a single quote, a double quote, or none.

edited Sep 7, 2015 at 8:58

answered Sep 4, 2015 at 4:06

Mariano

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4 Comments

Eduardo Henrique Over a year ago

What was the way i wanted was the following code: new RegExp('\['+tag+'(?:=["\']([^\]]+)["\'])?\]([\\s\\S]*?)\[/'+tag+']', 'gi');

Mariano Over a year ago

That code needs to be properly escaped. I assume you're now specifying: (a) you don't need the first group, and (b) the ='hello' part in the tag is optional but it should always have quotation marks. Code: result = new RegExp('\\['+tag+'(?:=(["\'])([^\\]]+)\\1)?\\]([\\s\\S]*?)\\[/'+tag+']','gi'); Live example

Eduardo Henrique Over a year ago

The best for me was the following: var re = new RegExp('\['+tag+'(?:=(["\']*)([^\]]+)\\1)?\]([\\s\\S]*?)\[/'+tag+']', 'gi');

Mariano Over a year ago

I don't understand why you are repeating the quotes in ["\']*. Check the escapes on that expression. When using the RegExp constructor, every backslash should be put as `\\`

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