Javascript RegExp quantifier issue

Question

I have some JavaScript that runs uses a replace with regular expressions to modify content on a page. I'm having a problem with a specific regex quantifier, though. All the documentation I've read (and I know it work in regex in other languages, too) says that JavaScript supports the {N}, {N,} and {N,N} quantifiers. That is, you can specify a particular number of matches you want, or a range of matches. E.g. (zz){5,} matches at least 10 z's in a row, and z{5,10} would match any number of z's from 5 to 10, no more and no less.

The problem is, I can match an exact number (e.g. z{5}) but not a range. The nearest I can figure is that it has something to do with the comma in the regex string, but I don't understand why and can't get around this. I have tried escaping the comma and even using the unicode hexidecimal string for comma (\u002C), but to no avail.

To clear up any possible misunderstandings, and to address some of the questions asked in the comments, here is some additional information (also found in the comments): I have tried creating the array in all possible ways, including var = [/z{5,}/gi,/a{4,5}/gi];, var = [new RegExp('z{5,}', 'gi'), new RegExp('a{4,5}', 'gi')];, as well as var[0] = new RegExp('z{5,}'), 'gi');, var[1] = /z{5,}/gi;, etc. The array is used in a for-loop as somevar.replace(regex[i], subst[i]);.

Answer 1

Perhaps I'm misunderstanding the question, but it seems like the Javascript implementation of the {n} operators is pretty good:

"foobar".match(/o{2,4}/); // => matches 'oo'
"fooobar".match(/o{2,4}/); // => matches 'ooo'
"foooobar".match(/o{2,4}/); // => matches 'oooo'
"fooooooobar".match(/o{2,4}/); // => matches 'oooo'
"fooooooobar".match(/o{2,4}?/); // => lazy, matches 'oo'
"foooobar".match(/(oo){2}/); // => matches 'oooo', and captures 'oo'
"fobar".match(/[^o](o{2,3})[^o]/); // => no match
"foobar".match(/[^o](o{2,3})[^o]/); // => matches 'foob' and captures 'oo'
"fooobar".match(/[^o](o{2,3})[^o]/); // => matches 'fooob' and captures 'oo'
"foooobar".match(/[^o](o{2,3})[^o]/); // => no match

Answer 2

It works for me.

var regex = [/z{5,}/gi,/a{4,5}/gi];
var subst = ['ZZZZZ','AAAAA'];
var somevar = 'zzzzz aaaaa aaaaaaa zzzzzzzzzz aaazzzaaaaaa';
print(somevar);
for (var i=0; i<2; i++) {
    somevar = somevar.replace(regex[i], subst[i]);
}
print(somevar);

output:

zzzzz aaaaa aaaaaaa zzzzzzzzzz aaazzzaaaaaa
ZZZZZ AAAAA AAAAAaa ZZZZZ aaazzzAAAAAa

The constructor version works, too:

var regex = [new RegExp('z{5,}','gi'),new RegExp('a{4,5}','gi')];

See it in action on ideone.com.

Answer 3

I think I've figured it out. I was building the array various ways to get it to work, but what I think made the difference was using single-quotes around the regex string, instead of leaving it open like [/z{5,}/,/t{7,9}/gi]. So when I did ['/z{5,}/','/t{7,9}/gi'] that seems to have fixed it. Even though, like in Alan's example, it does sometimes work fine without them. Just not in my case I guess.