Javascript regex not returning match

Question

I have a simple regex in which I'm trying to extract the leading value including the brackets. But for some reason it returns the entire string every time.

Sample string [1] My well-being if it includes [####] i want to then be able to get the contents of the match results so i can get [4] as a result.

const arr = [
  'I am not valid',
  '[1] My well-being',
  '[1] I conversation about',
  '[3] I role within',
  '[3] I members in the company',
  '[3]I priorities',
  '[3]How other teams',
  '[4] I within a team',
  '[4] I am a peer',
  '[4] I am a label',
  '[4] I am a label'
]

const regex = /^(\[\d+\])(.*)/img;
for (let index = 0; index < arr.length; index++) {
  const name = arr[index];
  const match = name.match(regex);
  console.log(match)
}

because that is what g does

epascarello
– epascarello

2022-02-04 18:14:12 +00:00
Commented Feb 4, 2022 at 18:14 — epascarello
– epascarello, Commented Feb 4, 2022 at 18:14
@epascarello I'd blame .*

VLAZ
– VLAZ

2022-02-04 18:14:45 +00:00
Commented Feb 4, 2022 at 18:14 — VLAZ
– VLAZ, Commented Feb 4, 2022 at 18:14

Caleb Denio · Accepted Answer · 2022-02-04 18:15:32Z

1

It's because of your use of the g flag.

To quote the documentation:

If the g flag is used, all results matching the complete regular expression will be returned, but capturing groups will not.

if the g flag is not used, only the first complete match and its related capturing groups are returned. In this case, the returned item will have additional properties as described below.

You can fix this by simply removing g from your regular expression, then name.match() will return capturing groups as well.

answered Feb 4, 2022 at 18:15

Caleb Denio

1,72512 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Barmar · Accepted Answer · 2022-02-04 18:19:35Z

If you only want the number in the brackets, leave out .* after it.

You also don't need any of the flags. i is for case-insensitive matching, but you don't have any letters. m makes ^ and $ match line endings, but you don't have any multi-line strings. And g is for foring all matches, but since the pattern is anchored there can only be one match.

And since the pattern is now the whole match, you don't need a capture group around it.

const arr = [
  'I am not valid',
  '[1] My well-being',
  '[1] I conversation about',
  '[3] I role within',
  '[3] I members in the company',
  '[3]I priorities',
  '[3]How other teams',
  '[4] I within a team',
  '[4] I am a peer',
  '[4] I am a label',
  '[4] I am a label'
]

const regex = /^\[\d+\]/;
for (let index = 0; index < arr.length; index++) {
  const name = arr[index];
  const match = name.match(regex);
  console.log(match)
}

Collectives™ on Stack Overflow

Javascript regex not returning match

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related