Parse shortcode with javascript

Question

I'm parsing a string like this with javascript:

[box style="a" width="b" height="c"]

So far, when I use http://gskinner.com/RegExr/ it works and it parses fine using this regex:

/(?<=\s).+?=".+?"/

However, when I do this in javascript it errors out:

Uncaught SyntaxError: Invalid regular expression: /(?<=\s).+?=".+?"/: Invalid group

This is part of the code:

if (scOpenTag instanceof Array) {
   var params = scOpenTag[0].match(/(?<=\s).+?=".+?"/);                    
   for (var i = 0; i < params.length; i++)
      console.log(params[i]);
}

Somebody know what I'm doing wrong?

Ωmega · Accepted Answer · 2012-10-27 16:45:04Z

2

Use simple regex pattern

[\w-]+="[^"]*"

answered Oct 27, 2012 at 16:45

Ωmega

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1 Comment

mb2o Over a year ago

Yes, that dit it! Thanks a lot guys

ruakh · Accepted Answer · 2012-10-27 16:38:43Z

1

JavaScript doesn't support lookbehind assertions; neither (?<=...) nor (?<!...) will work.

However, it looks like your keys/property-names/attribute-names/whatever-those-are have the form \w+, so you can get some mileage out of the word-boundary assertion \b (which matches either (?<!\w)(?=\w) or (?<=\w)(?!\w)):

/\b\w+="[^"]+"/

Edited to add: For that matter, you can get your exact current functionality by using a capture-group, and using params[1] instead of params[0]:

if (scOpenTag instanceof Array) {
   var params = scOpenTag[0].match(/\s(.+?=".+?")/);
   for (var i = 1; i < params.length; i++)
      console.log(params[i]);
}

answered Oct 27, 2012 at 16:38

ruakh

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3 Comments

mb2o Over a year ago

Hmmm, that's too bad. However, the params can also have space characters in them. So a string like [box style="metro action" url="someurl.com/"] would be applicable as well...

Ωmega Over a year ago

I see no reason to use \b in this case. If I am wrong, show me example of input where it makes difference.

ruakh Over a year ago

@Ωmega: Perhaps you know more about "this case" than I do. I'm working based on what was in the question. The OP felt the need to use a lookbehind assertion; I wanted to offer something more than "drop it".

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