I have a javascript function that works well with positive number but when input the negative number it alert NaN:

function formatMoney(number) {
        number = parseFloat(number.toString().match(/^\d+\.?\d{0,2}/));
        //Seperates the ponents of the number
        var ponents = (Math.floor(number * 100) / 100).toString().split(".");
        //Comma-fies the first part
        ponents [0] = ponents [0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
        //Combines the two sections
        return ponents.join(".");
    }
alert(formatMoney(-11));

Here is the example in jsFiddle /

thanks for any help

I have a javascript function that works well with positive number but when input the negative number it alert NaN:

function formatMoney(number) {
        number = parseFloat(number.toString().match(/^\d+\.?\d{0,2}/));
        //Seperates the ponents of the number
        var ponents = (Math.floor(number * 100) / 100).toString().split(".");
        //Comma-fies the first part
        ponents [0] = ponents [0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
        //Combines the two sections
        return ponents.join(".");
    }
alert(formatMoney(-11));

Here is the example in jsFiddle http://jsfiddle/longvu/wRYsU/

thanks for any help

• javascript

Share Follow edited Jun 19, 2013 at 2:19 John Koerner 38.1k88 gold badges9292 silver badges140140 bronze badges asked Jun 19, 2013 at 2:18 Long VuLong Vu 20511 gold badge33 silver badges1010 bronze badges 2

• What do you think .match(/^\d+\.?\d{0,2}/)) does? – zerkms Commented Jun 19, 2013 at 2:19
• If match does not find a match, it returns null, and parseFloat(null) returns NaN. – RobG Commented Jun 19, 2013 at 2:40

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2 Answers 2

Sorted by: Reset to default 5

There is no allowance for a leading sign in /^\d+\.?\d{0,2}/, it must start with a digit.

First step is to allow for that, with something like:

/^-?\d+\.?\d{0,2}/

If you place that in your example jsfiddle script, you get a dialog box with -11 rather than NaN.

Seems to me you can get rid of the first regular expression (unless you want to validate input) and use:

function formatAsMoney(n) {
  n = (Number(n).toFixed(2) + '').split('.');
  return n[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",") + '.' + (n[1] || '00');
}

There were once issues with toFixed, but I don't think it's a problem any more.