I just came across your site and found your regular expression tool. I recently created a similar tool and thought you might be interested in it. Especially since you have built a similar tool and likely thought through some of the similar ideas, I would love to get some feedback from you on what I have created.

The app is called the Flex 3 Regular Expression Explorer and can be found at my blog below.

http://blog.ryanswanson.com/2008/10/introducing-flex-3-regular-expression.html

The application is similar to the Flex Component and Style Explorers created by Adobe, but I have also added a collaborative community section where people can post their own regular expression examples as well as a full-feature help panel to get novices started with the technology.

Hope you like it!

Cheers,
Ryan

1. Regular expressions process strings one character at a time. Once a character has been included as part of a match, it can’t be part of a subsequent match in the same pattern.

2. Regular expressions use “greedy” matching by default. That means that a single part of a pattern will include as many characters as it can. So “.*” in your pattern is going to include as many characters as it can, as long as they’re followed by a “b”.

3. The global flag makes it so that you can get more than one result from a string; however, the captured results must be completely separate (a single character can’t be included in multiple matches — per rule #1)

4. There is a way to “override” rule 1 and allow characters to match more than one part of a pattern. To do this you use a “positive lookahead group”. Unfortunately, positive lookahead groups are also considered “noncapturing groups” — so you can’t “capture” matches. In your example the syntax using a positive lookahead group would be “(?=a.*b)” — notice that the original pattern is surrounded by “(?=” and “)”. Even though we can’t see it, I believe that it does technically match twice. My reasoning is because if you run a test with the pattern “((?=a.*b))” and the string “aab”, using RegExp.exec() you get two indexed matches. (In that example, the positive lookahead group is surrounded by a capturing group.) Unfortunately the matches are empty — I guess noncapturing groups’ content isn’t included in a surrounding capturing group.

I had a question about something I’m working on. I’m a beginner at regular expressions and they confused the hell out of me. If anyone actually knows how to do this stuff could you give me examples of code and/or explain to me in very simple terms what I have to do?

What I’ve done so far is gotten the source of a page to come back to me in the form of a string. In this source there’s a table (in html), which I sort of need to use to create a table of my own… I mean, with those numbers in that table. So I used a regular expression to take out everything between the two tags. I basically used this to do that : var pattern:RegExp = /(.*?)/;

But now, I’m trying to create a 2-d array and put the columns and rows from the html table into that. So does anyone know how I can do that? What code to use?

Thanks!