Formatting numbers with regex JavaScript

Question

I'm trying to format a number as brazilian currency, but I'm not sure what's going wrong.

function format2(n, currency) {
    return currency + " " + n.toFixed(2).replace(^\s*(?:[1-9]\d{0,2}(?:\.\d{3})*|0)(?:,\d{1,2})?$/g, "$1,");
}

R$ 123.456.789,10 thats how it should be.. i read that this regex would work but its giving me a syntax error.. — ledesma, Feb 25 '14 at 01:42
give examples of what you are actually passing to `format2()` — CrayonViolent, Feb 25 '14 at 01:58
no, you aren't reading the thread properly. a) the highest rated answer explicitly explains how to do it your way. b) rub some brain cells together and make adjustments to *any* of the answers (hint: swap the `,` and `.` in the code) — CrayonViolent, Feb 25 '14 at 02:06

Cilan · Answer 1 · 2014-02-25T02:03:08.533

1

Taken from the comments: “but its giving me a syntax error..”

You're missing a slash to define a regex literal. Change your return statement to

return currency + " " + n.toFixed(2).replace(/^\s*(?:[1-9]\d{0,2}(?:\.\d{3})*|0)(?:,\d{1,2})?$/g, "$1,");
                                             ^ Teda, the magic opening slash!

Btw, your regex is too complex IMO and doesn't format correctly. I would just do /\./g to get the matching periods, so your replace statement looks like .replace(/\./g, ",");

Demo

edited Feb 25 '14 at 02:03

answered Feb 25 '14 at 01:42

Cilan

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but its not formatting as it should... R$ 1.234,00 – ledesma Feb 25 '14 at 01:48
@GilbertoGonçalvesMachado What is the `,00`? When should it occur? I don't know much about brazilian currency formatting – Cilan Feb 25 '14 at 01:50
i see.. that fixed this problem.. but now i have the other problem that is not formatting the numbers.. – ledesma Feb 25 '14 at 01:52
@GilbertoGonçalvesMachado Please explain what you mean by `formatting the numbers..` – Cilan Feb 25 '14 at 01:52
,00 is the cents.. the format is: R$ 1,23 .. R$ 12,34 .. R$ 1.234,56 ... R$ 123.456,78 – ledesma Feb 25 '14 at 01:54
when i put format2(number).. its not giving me in the right format – ledesma Feb 25 '14 at 01:54
if i put format2(12345) its giving me 12345.00 – ledesma Feb 25 '14 at 01:55
@GilbertoGonçalvesMachado I'll try to help, I don't know much about regex... – Cilan Feb 25 '14 at 01:56
http://stackoverflow.com/questions/10300930/regex-to-validate-brazilian-money-using-javascript i got the regex sentence from this question.. they said it should work.. but i couldnt see how.. – ledesma Feb 25 '14 at 01:59
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/48317/discussion-between-the-wobbuffet-and-gilberto-goncalves-machado) – Cilan Feb 25 '14 at 02:00

score 0 · Answer 2 · answered Feb 25 '14 at 02:36

I don't know why you're so keen to use a regular expression for this. The following loop solution should be fine and offers a more general solution:

function formatNumber(num, places, thou, point) {
  var result = [];
  num = Number(num).toFixed(places).split('.');
  var m = num[0];

  for (var s=m.length%3, i=s?0:1, iLen=m.length/3|0; i<=iLen; i++) {
    result.push(m.substr(i? (i-1)*3+s : 0, i? 3 : s));
  }
  return result.join(thou) + point + num[1];
}

console.log('R$ ' + formatNumber(12345678.155, 2, '.', ',')); // R$ 12.345.678,16
console.log('R$ ' + formatNumber(12.155, 2, '.', ','));       // R$ 12,16

Formatting numbers with regex JavaScript

2 Answers2