Rails spinoffs - Jun 2006 - gsub vs. replace

I was looking at the gsub method on the String.prototype object in 
Prototype. I was trying to determine the purpose of this method. It 
seems like it duplicates the functionality of the built-in replace() 
method. So:

"red, blue, green".gsub(/, /, '' - '');
"red, blue, green".replace(/, /g, '' - '');

What is the difference between these lines?

Also both functions allow the second parameter to be a function 
(although with different arguments).

Finally both arguments allow parenthetical matches to be in the 
replacement string (although one uses #{n} and the other uses $n).

My question is why does gsub exist? Seems that although gsub is more 
ruby-like it is not needed and the replace() method suffices. Am I wrong?

Eric

On 6/3/06, Eric Anderson <eric-ANzg6odk14w@public.gmane.org> wrote:
> Also both functions allow the second parameter to be a function
> (although with different arguments).
Not in Internet Explorer 5. This is the sole reason why this function exists.

Bye,
  Martin