Having trouble with regular expression in javascript

Question

I am trying to construct a regular expression which parses mentions. e.g.

@aaa @bbb@ccc @dddd @eeee

it should match only aaa, dddd and eeee but not bbb@ccc

I have tried the following regular expression but it fails:

/(?:^|\s)@(\S+)/g

an example can be found here: https://regexr.com/3h9o5

anubhava · Accepted Answer · 2017-11-29 19:26:50Z

2

You can use this regex with \B and negated character class:

\B@([^@\s]+)(?=\s|$)

RegEx Breakup:

\B: assert position where \b does not match
[^@\s]+: Match 1 or more characters that are not @ and not a whitespace
(?=\s|$): Lookahead to assert that we have whitespace or end of line at next position

answered Nov 29, 2017 at 19:26

anubhava

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3 Comments

Thanks it works. But I am still not sure how \B works

I checked the pattern again. It fails here: regex101.com/r/7UH5K7/1

You can use: (?:^|\s)@([^@\s]+)(?=\s|$)

miggy92 · Accepted Answer · 2017-11-29 20:12:06Z

1

Your RE doesn't match because of \S. \S match @ too, so you need to replace it for what a name should be. Your RE should be something like

/(?:^|\s)@([^@\s]+)/g

Here it will match just 'aa' from '@aa@'. If you want whitespaces after the name you should use

/(?:^|\s)@([^@\s]+)(?=\s|$)/g

answered Nov 29, 2017 at 20:12

miggy92

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