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