Lazy match front part in JavaScript regex

Question

I have a string

Steve Jobs [email protected] somethingElse

I hope to match [email protected] somethingElse (a space in front)

This is my regular expression (JavaScript)

\s.+?@.+

But now it matches Jobs [email protected] somethingElse (a space in front)

I know I can use ? to lazy match the following part, but how to lazy match front part?

\s\S+@.+? There is no rightmost lazy matching, you'll either have to use a negated character class or a tempered greedy token approach. — Sebastian Proske
– Sebastian Proske, Commented Jan 16, 2018 at 8:52
Use (\S+@\S+)\s*(\S+) and extract first & second captured groups. — Tushar
– Tushar, Commented Jan 16, 2018 at 8:58

LukStorms · Accepted Answer · 2018-01-16 10:20:43Z

1

A . can be any character, including the whitespaces.

Normally e-mails don't contain whitespaces. (although it's actually allowed between 2 ")

So you could change the regex so that it looks for non-whitespaces \S before and after the @.
It can be greedy.

A whitespace followed by 1 or more non-whitespaces and a @ and 1 or more non-whitespaces. Then by whitespace(s) and something else:

\s(\S+@\S+)(?:\s+(\S+))?

edited Jan 16, 2018 at 10:20

answered Jan 16, 2018 at 8:59

LukStorms

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2 Comments

Hongbo Miao Over a year ago

I tried Tushar and gurvinder372's too, and they both work. But I feel this one with \S help is a very smart solution!

LukStorms Over a year ago

Well, something like \S+@\S+ is short alright. But it would also capture a string with more than 1 @. Something like [^\s@]+[@][^\s@]+[.]\w+ would be slightly more accurate to capture an e-mail.

gurvinder372 · Accepted Answer · 2018-01-16 08:58:10Z

1

You can also use trim, split and pop

var output = "Steve Jobs [email protected] ".trim().split(" ").pop();

Regex solution

You can use trim and match

var output = "Steve Jobs [email protected] ".trim().match( /[\w.]+@[\w.]+/g )

Regex - /[\w.]+@[\w.]+$/gi

Edit

var output = "Steve Jobs [email protected] somethingelse ".trim().match( /[\w.]+@[\w.]+/g )

Demo

var  regex = /[\w.]+@[\w.]+/g;

var input1 = "Steve Jobs [email protected] ";
var input2 = "Steve Jobs [email protected] somethingelse ";

var fn = (str) => str.trim().match(regex);

console.log( fn(input1) );
console.log( fn(input2) );

edited Jan 16, 2018 at 8:58

answered Jan 16, 2018 at 8:51

gurvinder372

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2 Comments

Hongbo Miao Over a year ago

Thanks, I updated my questions a little bit by adding somethingElse, to reveal the more complex real problem. (Sorry, I think I simplified too much at first)

gurvinder372 Over a year ago

@HongboMiao Please try the regex solution as well.

Tugay İlik · Accepted Answer · 2018-01-16 08:58:59Z

0

The allowed characters in an email are;

*0-9* | *a-z* | *. - _*

And it must have a @ symbol too.

So our regex must start with allowed characters,

[a-zA-z0-9-_.]

It must continue with @ symbol;

[a-zA-z0-9-_.]+@

Then it can end with .com or anything which includes dot

[a-zA-z0-9-_.]+@[a-zA-z0-9.]+

answered Jan 16, 2018 at 8:58

Tugay İlik

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