Insert character after every nth character

Question

I'm trying to convert a number like: 1215464565 into 12-15-46-45-65. I'm trying to do this:

var num = 1215464565; 
num = num.toString();
num.replace(/(.{2)/g,"-1");

The JSFiddle, however doesn't reflect this change though.

@AvinashRaj it works (all pairs of digits are replaced with "-1" in `1215464565`). If you ask what is the point to replace pairs of digits with "-1" while hyphens between pairs of digits are required - I don't know, I just fixed OP code line. — Regent, Nov 14 '14 at 05:35

score 16 · Accepted Answer · answered Nov 13 '14 at 14:00

16

var num = 1215464565; 
var newNum = num.toString().match(/.{2}/g).join('-');
console.log(newNum);

jsFiddle example

answered Nov 13 '14 at 14:00

j08691

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IMHO this is the most readable solution! +1 – Renato Gama Nov 13 '14 at 14:04
pretty cool, good to go! – Aug 30 '17 at 02:50
3

This only works if `num` is exactly divisible by the split number otherwise the last block is missed off use `match(/.{1,2}/g` to ensure the last chars are shown. – chris Jan 12 '18 at 10:31
1

If the string is empty then this throws an error `match(/.{0,2}/g).join(' ').trim().replace(/\s/g, '-');` works for empty strings, one character strings and everything after that. But we are getting a bit verbose. – nidal Oct 09 '18 at 15:57

Avinash Raj · Answer 2 · 2014-11-13T14:08:50.223

Use the below regex in replace function

(?!^)(\d{2})(?=(?:\d{2})*$)

and then replace the matched digits with -$1

DEMO

> var num = 1215464565;
undefined
> num = num.toString();
'1215464565'
> num.replace(/(?!^)(\d{2})(?=(?:\d{2})*$)/g, '-$1')
'12-15-46-45-65'

Regular Expression:

(?!                      look ahead to see if there is not:
  ^                        the beginning of the string
)                        end of look-ahead
(                        group and capture to \1:
  \d{2}                    digits (0-9) (2 times)
)                        end of \1
(?=                      look ahead to see if there is:
  (?:                      group, but do not capture (0 or more
                           times):
    \d{2}                    digits (0-9) (2 times)
  )*                       end of grouping
  $                        before an optional \n, and the end of
                           the string
)                        end of look-ahead

score 1 · Answer 3 · answered Nov 13 '14 at 14:02

1

This should work for you:

var num = 1215464565; 
num = num.toString();
for(var i = 2; i < num.length; i = i + 2)
{
    num = [num.slice(0, i), "-", num.slice(i)].join('');
    i++;
}
window.alert("" + num);

answered Nov 13 '14 at 14:02

brso05

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Insert character after every nth character

3 Answers3

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