Question

I thought the community helped me nail this problem w/a case insensitive RegExp, but I got it wrong. What about the following RegEx fails in IE7 and IE8?

var reggy = /(\s*?)<span\b(?:.*?)(?:class=(?:'|"|.*?\s)?foobar(?:\s|\3))(?:.*?)(?:\/)?>(.+?)<\/span>(\s*?)/ig;

jsFiddle here. Only in IE7 and IE8 does it give a “did not match” result.

Answer 1

There are several problems with that regex, the worst of them being that you seem to be mixing up capturing and non-capturing groups. As Mike Samuel hinted, the third capturing group is the (\s*?) at the very end (which, like the one at the beginning, served no useful purpose). Try this regex:

/<span\b[^>]*\bclass=\s*(['"]?)forbes_entity\1[^>]*>[\s\S]*?<\/span>/ig

Here there’s only the one capturing group; it captures a single-quote, a double-quote, or nothing. After the class name, the \1 matches the same thing again. (I changed the class name to match the sample text in your fiddle.)

It turned out I didn’t need any other groups, but if I had needed them I would have used non-capturing groups ( (?:...) ) to make it easier to keep track of the capturing-group numbers. I also used [\s\S] instead of . to match the span’s contents, in case it contains any newlines.