Regex matching dates in a string in Javascript

Question

Following up from this thread, im trying to make this work

JavaScript regular expression to match X digits only

string = '2016-2022'
re = /\d{4}/g
result = [...string.matchAll(re)]

This returns an array of two arrays. Is there a way to consolidate this into 1 array?

However it doesn't look like this is returning the desired results

I'm new to regular expression. What am I doing wrong?

*This returns an array of two arrays. Is there a way to consolidate this into 1 array?* `[...string.matchAll(re)].flat()`. If the structure is set `'2016-2022'.split('-')` might be an alternative. — Lain, Apr 08 '22 at 12:52
_"Is there a way to consolidate this into 1 array?"_ -> [How much research effort is expected of Stack Overflow users?](https://meta.stackoverflow.com/questions/261592/how-much-research-effort-is-expected-of-stack-overflow-users), e.g. _"Yes, you can map or loop through the match results with for-of to build your own array."_ as mentioned on your [previous, quite similar question](https://stackoverflow.com/questions/71797198/javascript-regex-match-4-digits) — Andreas, Apr 08 '22 at 13:20

score 0 · Answer 1 · answered Apr 08 '22 at 12:51

0

this return an array of matches

result = string.match(re)

answered Apr 08 '22 at 12:51

Simone Celia

144
1
5
11

I need to use matchAll, not just match – Morgan Allen Apr 08 '22 at 12:51
Why do you need to use matchAll? – Daniel Beck Apr 08 '22 at 12:55

score 0 · Answer 2 · answered Apr 08 '22 at 12:54

This is a function to parse the string encoding those two year values and return the inner years as items of an array:

let o = parseYearsInterval('2016-2022');
console.log(o);

function parseYearsInterval(encodedValue){
  var myregexp = /(\d{4})-(\d{4})/;
  var match = myregexp.exec(encodedValue);
  if (match != null) {
    let d1 = match[1];
    let d2 = match[2];
    //return `[${d1}, ${d2}]`;
    let result = [];
    result.push(d1);
    result.push(d2);
    return result;
  } else {
    return "not valid input";
  }
}

I think there are better ways to do that like splitting the string against the "-" separator and return that value as is like:

console.log ( "2016-2022".split('-') )

Scriptkiddy1337 · Answer 3 · 2022-04-12T13:05:13.463

0

var str = '2016-2022';
var result = [];
str.replace(/\d{4}/g, function(match, i, original) {
    result.push(match);
    return '';
});
console.log(result);

I also wanted to mention, that matchAll does basicly nothing else then an while exec, that's why you get 2 arrays, you can do it by yourself in a while loop and just save back what you need

var result = [];
var matches;
var regexp = /\d{4}/g;
while (matches = regexp.exec('2016-2022')) result.push(matches[0]);
console.log(result);

edited Apr 12 '22 at 13:05

answered Apr 08 '22 at 12:55

Scriptkiddy1337

774
4
9

Add a `console.log()`. – Lain Apr 08 '22 at 12:57
1

Your second snippet does not terminate. – Lain Apr 12 '22 at 06:04

score 0 · Answer 4 · answered Apr 08 '22 at 12:56

0

Just do a split if you know that only years are in the string and the strucutre isn't changing:

let arr = str.split("-");

answered Apr 08 '22 at 12:56

John_H_Smith

160
12

score 0 · Answer 5 · answered Apr 08 '22 at 14:16

Question

string = '2016-2022'
re = /\d{4}/g
result = [...string.matchAll(re)]
This returns an array of two arrays. Is there a way to consolidate this into 1 array?

Solution

You may simply flat the result of matchAll.

let string = '2016-2022'
let re = /\d{4}/g
console.log([...string.matchAll(re)].flat())

Alternative

If your structure is given like "yyyy-yyyy-yyyy" you might consider a simple split

console.log('2016-2022'.split('-'))

Regex matching dates in a string in Javascript

5 Answers5

Question

Solution

Alternative