How to convert Java Regex to JS regex?

Question

Java Regex:

String regex = "(?i)^[\\w.-][\\+\\w.-]*+@[\\w.-]+\\.[a-z]{2,4}$";
  Pattern  pattern = Pattern.compile(regex);
  Matcher matcher = pattern.matcher("[email protected]");
 System.out.println(matcher.matches());

JS Regex:

 var regex = /^[\w.-][\w\+.-]*+@[\w.-]+\.[a-z]{2,4}$/i;

But JS regex is not a valid expression. Not sure what I am missing here. Please guide

Ry- · Accepted Answer · 2017-07-11 15:06:58Z

1

*+ is a possessive quantifier. It’s like *, but fails the match if it has to match less than what’s available to it. Since @ doesn’t match [\w\+.-] anyway, though, you can just replace it with *.

var regex = /^[\w.-][\w\+.-]*@[\w.-]+\.[a-z]{2,4}$/i;

Also, don’t use this regex to validate e-mail addresses; it’s incorrect. See Regex validation of email addresses according to RFC5321/RFC5322 for a correct one.

answered Jul 11, 2017 at 15:06

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Ry-

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user6560716 · Accepted Answer · 2017-07-11 15:07:11Z

0

Try:

/^[\w.-][\w\+.-]*@[\w.-]+\.[a-z]{2,4}$/i

I removed the + after the *, because JavaScript doesn't support possessive quantifier.

You can try this regex here: https://regex101.com/r/FmUF5M/1

answered Jul 11, 2017 at 15:07

user6560716

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