Proposal for exact matching and matching at a position in RegExp

Steve L. steves_list at
Sun Feb 14 06:04:18 PST 2010

On Feb 14, 2010, at 1:40 AM, Brendan Eich wrote:

>> compatibility with other regex flavors is probably good enough  reason to 
>> chose \G over /y.
> Not clear, since ES3 deviated from Perl and will not reconverge. The 
> committee is not going to standardize any lastIndex or pos mapping per 
> target string and regex pair, I am pretty sure.

That seems a reasonable position for the committee to take. To be clear, are 
you suggesting that \G be ruled out, but leaving the door open for 
standardizing /y?

> Perhaps with enough string- and byte-buffer performance, the JS  library 
> ecosystem can promulgate a new class, call it RegEx, which has  the best 
> consensus API, and built-in RegExp can try to fade away.

That would be quite interesting to see, but since there are just a few, 
mostly tolerable design issues with the existing ES RegExp API, I can only 
envision a switch to a JS library over built-in RegExp being justified if 
the library included pretty much all the features of ES regexes and added 
significant new features including better Unicode support. In the near term, 
the resulting file size would pretty much assure low adoption in 

Since I don't have much hope for a reasonable alternative to RegExp, I think 
it's important to continue looking at RegExp improvements for future ES 
versions. I have a laundry list of desired changes and additions, but the 
three things I'd like to see first are /x, /y, and atomic groups. But now 
I'm off topic again, so I'll just leave it there. :)

Steven Levithan

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