带有九对以上括号的正则表达式

Question

I have a regular expression with ten pairs of brackets. With RegExp.$n I need to access bracket pair 1, 2 and 10. In JS it's only possible to access the bracket pairs up to number 9. Since I need not to access pairs 3 to 9 is there a way to change the regular expression such those brackets don't count? Then I could access bracket pair 9 by RegExp.$3 . I'm also happy with any other solution to this problem. Thanks!

Answer 1

The match result is indexable by the group number (where there's always an implicit group 0 for the whole match):

> "banana".match(/()()()()()()()()()()(na)+/)[11]
"na"
> "banana".match(/()()()()()()()()()()(na)+/)[0]
"nana"

// Works with exec too
> /()()()()()()()()()()(na)+/.exec("banana")[11]
"na"

Note that within replace() , there doesn't seem to be a restriction on the group number:

> "banana".replace(/()()()()()()()()()()(na)+/, "[$11]")
"ba[na]"

To answer the other part of your question -- yes, it is indeed possible to have create what are called non-capturing groups using the (?:foo) syntax instead of (foo) .

Answer 2

You can create non-capturing groups with ?: for things that you don't need to access later.

"rex".match(/(r)(?:e)(x)/)
// ["rex", "r", "x"]