regex to find consecutive digits in javascript

Question

I'm trying to find multiple consecutive digits through regex in javascript

Let's say I've got:

12345abc123

I want to know how many times I've got 3 or more consecutive digits. Right now I'm using:

/\d{3}/g

But that gives me: 123, 123 and I want to have: 123, 234, 345, 123

How can I change my regex to get want I want?

anubhava · Accepted Answer · 2014-07-23T07:57:00.287

8

You can use this regex:

/(?=(\d{3}))/g

Online Regex Demo

Code:

var re = /(?=(\d{3}))/g; 
var str = '12345abc789';
var m;
while ((m = re.exec(str)) != null) {
    console.log(m[1]);
}

Output:

edited Jul 23 '14 at 07:57

answered Jul 23 '14 at 07:43

anubhava

761,203
64
569
643

1

Great! Thanks a lot, I was trying it with grouping but did not hit the good one – subarroca Jul 23 '14 at 07:53
@anubhava Why you added `.` at the last? – Avinash Raj Jul 23 '14 at 07:55
the `.` at the end of your regular expression should be removed – North Jul 23 '14 at 07:56
It will work without it since grouping is inside the lookahead. (updated the regex) – anubhava Jul 23 '14 at 07:57

Ja͢ck · Answer 2 · 2014-07-23T07:56:27.487

4

You'd have to use look-ahead assertions:

var str = '12345abc123', 
re = /\d(?=(\d\d))/g;

while ((match = re.exec(str)) !== null) {
    // each match is an array comprising
    // - the first digit and
    // - the next two digits
    console.log(match.join(''));
}

It matches a digit if followed by another two; the assertion causes the engine to start the next search right after the first matched digit.

edited Jul 23 '14 at 07:56

answered Jul 23 '14 at 07:49

Ja͢ck

170,779
38
263
309

North · Answer 3 · 2014-07-23T07:53:48.013

1

This is the regex you are looking for:

/(?=(\d{3}))/g

edited Jul 23 '14 at 07:53

answered Jul 23 '14 at 07:46

North

90
4

regex to find consecutive digits in javascript

3 Answers3

Online Regex Demo

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