Does the RegExp /y modifier require /g?

Brendan Eich brendan at
Mon Dec 24 13:15:00 PST 2007

On Dec 24, 2007, at 8:44 AM, StevenLevithan wrote:

> (I emailed this to the list last night, but it doesn't seem to have  
> gone
> through. Sorry if this becomes a dupe.)

(I don't see a moderator request based on your sending from a  
different e-mail address -- I don't see a dup either.)

> Given the above rule, my questions are:
> 1. Does ES4's /y (sticky) modifier have any meaning if the /g (global)
> modifier is not also set?


> 2. What about with String.prototype.split and  
>, which
> ignore the values of and regexp.lastIndex?

The /y flag makes unanchored regexps match or fail at the current  
position in the target string, period. Where the current position is  
may depend on /g and other things, but /y is independent (lower- 
level) than these considerations.

> I'm working on code which brings some of the ES4 regex features  
> (including
> /y) to current browsers, but I'm not sure which way to go on these  
> points.

Firefox 3 is in beta release now and has supported /y since an early  
alpha. See


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