How to add spaces to every two numbers with JavaScript?

Question

I like to output a formatted number with a space after every two numbers, I've tried this:

 function twoSpaceNumber(num) {
    return num.toString().replace(/\B(?<!\.\d)(?=([0-9]{2})+(?!\d))/g, " ");
}

twoSpaceNumber(12345678) => 1 23 45 67 89 ( should start with 12 ? )

and also when it starts with 0 I had very strange output

twoSpaceNumber(012345678) => 12 34 56 78

Pass `num` as a string, not a number, else the leading zeros will disappear and use `.replace(/\d{2}/g, '$& ')` — Wiktor Stribiżew, Oct 14 '20 at 20:44
Does it matter if the characters are in the range "0" to "9", or do you just want to insert a space after every two characters? — Andrew Morton, Oct 14 '20 at 20:48
Is the format you want to use some usual format in a particular culture? There migh tbe something already made for that. — Andrew Morton, Oct 14 '20 at 21:13

score 2 · Answer 1 · answered Oct 14 '20 at 21:19

Pass num as a string, not a number, else the leading zeros will disappear and use

function twoSpaceNumber(num) {
  return num.replace(/\d{2}(?!$)/g, "$& ");
}

The regex matches two digits that are not at the end of string (in order not to add a space at the string end).

JavaScript demo

const regex = /\d{2}(?!$)/g;
function twoSpaceNumber(num) {
  return num.replace(regex, "$& ");
}
const strings = ['123456789','012345678'];
for (const string of strings) {
  console.log(string, '=>', twoSpaceNumber(string));
}

Andrew Morton · Answer 2 · 2020-10-14T21:09:38.750

1

Please consider

var s = "1234456";
var t = s.match(/.{1,2}/g);
var u = t.join(" ");
console.log(u);

which logs

12 34 45 6

and

var s = "ABCDEF";
var t = s.match(/.{1,2}/g);
var u = t.join(" ");
console.log(u);

which logs

AB CD EF

Note that s is a string.

Is that what you need?

edited Oct 14 '20 at 21:09

answered Oct 14 '20 at 20:57

Andrew Morton

24,203
9
60
84

score 0 · Answer 3 · answered Oct 14 '20 at 20:55

0

If you don't mind a non-regex approach:

function twoSpaceNumber(num) { 
    var res = '';
    num += '';
    for(var i = 0; i < num.length; i+=2)
    {    
        res += num.substr(i,2) + ' ';
    }
    return res.trim();
}

answered Oct 14 '20 at 20:55

Paulo Ricca

26
5

Do remember that if you want a 0 at the front of the number, you need to pass it as a string otherwise javascript will ignore it – Paulo Ricca Oct 14 '20 at 20:58

How to add spaces to every two numbers with JavaScript?

3 Answers3