2024-05-06 20:40:05 +00:00
|
|
|
---
|
2024-10-30 17:34:11 +00:00
|
|
|
date: 2020-11-04
|
2024-05-06 20:40:05 +00:00
|
|
|
id: 66a8f9f2-9d57-4467-bf41-a84eb4b3d10d
|
|
|
|
|
title: JavaScript RegExp Numbered Capture Groups
|
|
|
|
|
---
|
|
|
|
|
|
|
|
|
|
# Examples
|
|
|
|
|
|
|
|
|
|
## Subexpressions
|
|
|
|
|
|
|
|
|
|
When the regular expression contains subexpressions grouped with
|
|
|
|
|
parentheses, the text that matched those groups will also show up in the
|
|
|
|
|
array. The whole match is always the first element. The next element is
|
|
|
|
|
the part matched by the first group (the one whose opening parenthesis
|
|
|
|
|
comes first in the expression), then the second group, and so on.
|
|
|
|
|
|
|
|
|
|
``` javascript
|
|
|
|
|
let quotedText = /'([^']*)'/;
|
|
|
|
|
console.log(quotedText.exec("she said 'hello'"));
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## No matches
|
|
|
|
|
|
|
|
|
|
When a group does not end up being matched at all (for example, when
|
|
|
|
|
followed by a question mark), its position in the output array will hold
|
|
|
|
|
undefined. Similarly, when a group is matched multiple times, only the
|
|
|
|
|
last match ends up in the array.
|
|
|
|
|
|
|
|
|
|
``` javascript
|
|
|
|
|
console.log(/bad(ly)?/.exec("bad"));
|
|
|
|
|
console.log(/(\d)+/.exec("123"));
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
# See also
|
|
|
|
|
|
|
|
|
|
[Named capture
|
|
|
|
|
groups](20201104100431-javascript_regexp_named_capture_groups)
|
