How can I format numbers as dollars currency strin

Question

I would like to format a price in JavaScript.
I'd like a function which takes a float as an argument and returns a string formatted like this:

"$ 2,500.00"

What's the best way to do this?

Answer 1

Patrick Desjardins (ex Daok)'s example worked well for me. I ported over to coffeescript if anyone is interested.

Number.prototype.toMoney = (decimals = 2, decimal_separator = ".", thousands_separator = ",") ->
    n = this
    c = if isNaN(decimals) then 2 else Math.abs decimals
    sign = if n < 0 then "-" else ""
    i = parseInt(n = Math.abs(n).toFixed(c)) + ''
    j = if (j = i.length) > 3 then j % 3 else 0
    x = if j then i.substr(0, j) + thousands_separator else ''
    y = i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousands_separator)
    z = if c then decimal_separator + Math.abs(n - i).toFixed(c).slice(2) else ''
    sign + x + y + z

Answer 2

There is a javascript port of the PHP function "number_format".

I find it very usefull as it is easy to use and recognisable for PHP developers.

function number_format (number, decimals, dec_point, thousands_sep) {
    var n = number, prec = decimals;

    var toFixedFix = function (n,prec) {
        var k = Math.pow(10,prec);
        return (Math.round(n*k)/k).toString();
    };

    n = !isFinite(+n) ? 0 : +n;
    prec = !isFinite(+prec) ? 0 : Math.abs(prec);
    var sep = (typeof thousands_sep === 'undefined') ? ',' : thousands_sep;
    var dec = (typeof dec_point === 'undefined') ? '.' : dec_point;

    var s = (prec > 0) ? toFixedFix(n, prec) : toFixedFix(Math.round(n), prec); 
    //fix for IE parseFloat(0.55).toFixed(0) = 0;

    var abs = toFixedFix(Math.abs(n), prec);
    var _, i;

    if (abs >= 1000) {
        _ = abs.split(/\D/);
        i = _[0].length % 3 || 3;

        _[0] = s.slice(0,i + (n < 0)) +
               _[0].slice(i).replace(/(\d{3})/g, sep+'$1');
        s = _.join(dec);
    } else {
        s = s.replace('.', dec);
    }

    var decPos = s.indexOf(dec);
    if (prec >= 1 && decPos !== -1 && (s.length-decPos-1) < prec) {
        s += new Array(prec-(s.length-decPos-1)).join(0)+'0';
    }
    else if (prec >= 1 && decPos === -1) {
        s += dec+new Array(prec).join(0)+'0';
    }
    return s; 
}

(Comment block from the original, included below for examples & credit where due)

// Formats a number with grouped thousands
//
// version: 906.1806
// discuss at: http://phpjs.org/functions/number_format
// +   original by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
// +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// +     bugfix by: Michael White (http://getsprink.com)
// +     bugfix by: Benjamin Lupton
// +     bugfix by: Allan Jensen (http://www.winternet.no)
// +    revised by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
// +     bugfix by: Howard Yeend
// +    revised by: Luke Smith (http://lucassmith.name)
// +     bugfix by: Diogo Resende
// +     bugfix by: Rival
// +     input by: Kheang Hok Chin (http://www.distantia.ca/)
// +     improved by: davook
// +     improved by: Brett Zamir (http://brett-zamir.me)
// +     input by: Jay Klehr
// +     improved by: Brett Zamir (http://brett-zamir.me)
// +     input by: Amir Habibi (http://www.residence-mixte.com/)
// +     bugfix by: Brett Zamir (http://brett-zamir.me)
// *     example 1: number_format(1234.56);
// *     returns 1: '1,235'
// *     example 2: number_format(1234.56, 2, ',', ' ');
// *     returns 2: '1 234,56'
// *     example 3: number_format(1234.5678, 2, '.', '');
// *     returns 3: '1234.57'
// *     example 4: number_format(67, 2, ',', '.');
// *     returns 4: '67,00'
// *     example 5: number_format(1000);
// *     returns 5: '1,000'
// *     example 6: number_format(67.311, 2);
// *     returns 6: '67.31'
// *     example 7: number_format(1000.55, 1);
// *     returns 7: '1,000.6'
// *     example 8: number_format(67000, 5, ',', '.');
// *     returns 8: '67.000,00000'
// *     example 9: number_format(0.9, 0);
// *     returns 9: '1'
// *     example 10: number_format('1.20', 2);
// *     returns 10: '1.20'
// *     example 11: number_format('1.20', 4);
// *     returns 11: '1.2000'
// *     example 12: number_format('1.2000', 3);
// *     returns 12: '1.200'

Answer 3

I found this from: accounting.js . Its very easy and perfectly fits my need.

// Default usage:
accounting.formatMoney(12345678); // $12,345,678.00

// European formatting (custom symbol and separators), can also use options object as second parameter:
accounting.formatMoney(4999.99, "€", 2, ".", ","); // €4.999,99

// Negative values can be formatted nicely:
accounting.formatMoney(-500000, "£ ", 0); // £ -500,000

// Simple `format` string allows control of symbol position (%v = value, %s = symbol):
accounting.formatMoney(5318008, { symbol: "GBP",  format: "%v %s" }); // 5,318,008.00 GBP

// Euro currency symbol to the right
accounting.formatMoney(5318008, {symbol: "€", precision: 2, thousand: ".", decimal : ",", format: "%v%s"}); // 1.008,00€ 

Answer 4

Number.prototype.toFixed

This solution is compatible with every single major browser:

  const profits = 2489.8237;

  profits.toFixed(3) //returns 2489.824 (rounds up)
  profits.toFixed(2) //returns 2489.82
  profits.toFixed(7) //returns 2489.8237000 (pads the decimals)

All you need is to add the currency symbol (e.g. "$" + profits.toFixed(2)) and you will have your amount in dollars.

Custom function

If you require the use of , between each digit, you can use this function:

function formatMoney(n, c, d, t) {
  var c = isNaN(c = Math.abs(c)) ? 2 : c,
    d = d == undefined ? "." : d,
    t = t == undefined ? "," : t,
    s = n < 0 ? "-" : "",
    i = String(parseInt(n = Math.abs(Number(n) || 0).toFixed(c))),
    j = (j = i.length) > 3 ? j % 3 : 0;

  return s + (j ? i.substr(0, j) + t : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + t) + (c ? d + Math.abs(n - i).toFixed(c).slice(2) : "");
};

document.getElementById("b").addEventListener("click", event => {
  document.getElementById("x").innerText = "Result was: " + formatMoney(document.getElementById("d").value);
});

<label>Insert your amount: <input id="d" type="text" placeholder="Cash amount" /></label>
<br />
<button id="b">Get Output</button>
<p id="x">(press button to get output)</p>

Use it like so:

(123456789.12345).formatMoney(2, ".", ",");

If you're always going to use '.' and ',', you can leave them off your method call, and the method will default them for you.

(123456789.12345).formatMoney(2);

If your culture has the two symbols flipped (i.e. Europeans) and you would like to use the defaults, just paste over the following two lines in the formatMoney method:

    d = d == undefined ? "," : d, 
    t = t == undefined ? "." : t, 

Custom function (ES6)

If you can use modern ECMAScript syntax (i.e. through Babel), you can use this simpler function instead:

function formatMoney(amount, decimalCount = 2, decimal = ".", thousands = ",") {
  try {
    decimalCount = Math.abs(decimalCount);
    decimalCount = isNaN(decimalCount) ? 2 : decimalCount;

    const negativeSign = amount < 0 ? "-" : "";

    let i = parseInt(amount = Math.abs(Number(amount) || 0).toFixed(decimalCount)).toString();
    let j = (i.length > 3) ? i.length % 3 : 0;

    return negativeSign + (j ? i.substr(0, j) + thousands : '') + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousands) + (decimalCount ? decimal + Math.abs(amount - i).toFixed(decimalCount).slice(2) : "");
  } catch (e) {
    console.log(e)
  }
};
document.getElementById("b").addEventListener("click", event => {
  document.getElementById("x").innerText = "Result was: " + formatMoney(document.getElementById("d").value);
});

<label>Insert your amount: <input id="d" type="text" placeholder="Cash amount" /></label>
<br />
<button id="b">Get Output</button>
<p id="x">(press button to get output)</p>

Answer 5

Here's the best js money formatter I've seen:

Number.prototype.formatMoney = function(decPlaces, thouSeparator, decSeparator) {
    var n = this,
        decPlaces = isNaN(decPlaces = Math.abs(decPlaces)) ? 2 : decPlaces,
        decSeparator = decSeparator == undefined ? "." : decSeparator,
        thouSeparator = thouSeparator == undefined ? "," : thouSeparator,
        sign = n < 0 ? "-" : "",
        i = parseInt(n = Math.abs(+n || 0).toFixed(decPlaces)) + "",
        j = (j = i.length) > 3 ? j % 3 : 0;
    return sign + (j ? i.substr(0, j) + thouSeparator : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thouSeparator) + (decPlaces ? decSeparator + Math.abs(n - i).toFixed(decPlaces).slice(2) : "");
};

It was re-formatted and borrowed from here: https://stackoverflow.com/a/149099/751484

You'll have to supply your own currency designator (you used $ above).

Call it like this (although note that the args default to 2, comma, & period, so you don't need to supply any args if that's your preference):

var myMoney=3543.75873;
var formattedMoney = '$' + myMoney.formatMoney(2,',','.'); // "$3,543.76"

Answer 6

Here are some solutions, all pass the test suite, test suite and benchmark included, if you want copy and paste to test, try This Gist.

Method 0 (RegExp)

Base on https://stackoverflow.com/a/14428340/1877620, but fix if there is no decimal point.

if (typeof Number.prototype.format === 'undefined') {
    Number.prototype.format = function (precision) {
        if (!isFinite(this)) {
            return this.toString();
        }

        var a = this.toFixed(precision).split('.');
        a[0] = a[0].replace(/\d(?=(\d{3})+$)/g, '$&,');
        return a.join('.');
    }
}

Method 1

if (typeof Number.prototype.format === 'undefined') {
    Number.prototype.format = function (precision) {
        if (!isFinite(this)) {
            return this.toString();
        }

        var a = this.toFixed(precision).split('.'),
            // skip the '-' sign
            head = Number(this < 0);

        // skip the digits that's before the first thousands separator 
        head += (a[0].length - head) % 3 || 3;

        a[0] = a[0].slice(0, head) + a[0].slice(head).replace(/\d{3}/g, ',$&');
        return a.join('.');
    };
}

Method 2 (Split to Array)

if (typeof Number.prototype.format === 'undefined') {
    Number.prototype.format = function (precision) {
        if (!isFinite(this)) {
            return this.toString();
        }

        var a = this.toFixed(precision).split('.');

        a[0] = a[0]
            .split('').reverse().join('')
            .replace(/\d{3}(?=\d)/g, '$&,')
            .split('').reverse().join('');

        return a.join('.');
    };
}

Method 3 (Loop)

if (typeof Number.prototype.format === 'undefined') {
    Number.prototype.format = function (precision) {
        if (!isFinite(this)) {
            return this.toString();
        }

        var a = this.toFixed(precision).split('');
        a.push('.');

        var i = a.indexOf('.') - 3;
        while (i > 0 && a[i-1] !== '-') {
            a.splice(i, 0, ',');
            i -= 3;
        }

        a.pop();
        return a.join('');
    };
}

Usage Example

console.log('======== Demo ========')
console.log(
    (1234567).format(0),
    (1234.56).format(2),
    (-1234.56).format(0)
);
var n = 0;
for (var i=1; i<20; i++) {
    n = (n * 10) + (i % 10)/100;
    console.log(n.format(2), (-n).format(2));
}

Separator

If we want custom thousands separator or decimal separator, use replace():

123456.78.format(2).replace(',', ' ').replace('.', ' ');

Test suite

function assertEqual(a, b) {
    if (a !== b) {
        throw a + ' !== ' + b;
    }
}

function test(format_function) {
    console.log(format_function);
    assertEqual('NaN', format_function.call(NaN, 0))
    assertEqual('Infinity', format_function.call(Infinity, 0))
    assertEqual('-Infinity', format_function.call(-Infinity, 0))

    assertEqual('0', format_function.call(0, 0))
    assertEqual('0.00', format_function.call(0, 2))
    assertEqual('1', format_function.call(1, 0))
    assertEqual('-1', format_function.call(-1, 0))
    // decimal padding
    assertEqual('1.00', format_function.call(1, 2))
    assertEqual('-1.00', format_function.call(-1, 2))
    // decimal rounding
    assertEqual('0.12', format_function.call(0.123456, 2))
    assertEqual('0.1235', format_function.call(0.123456, 4))
    assertEqual('-0.12', format_function.call(-0.123456, 2))
    assertEqual('-0.1235', format_function.call(-0.123456, 4))
    // thousands separator
    assertEqual('1,234', format_function.call(1234.123456, 0))
    assertEqual('12,345', format_function.call(12345.123456, 0))
    assertEqual('123,456', format_function.call(123456.123456, 0))
    assertEqual('1,234,567', format_function.call(1234567.123456, 0))
    assertEqual('12,345,678', format_function.call(12345678.123456, 0))
    assertEqual('123,456,789', format_function.call(123456789.123456, 0))
    assertEqual('-1,234', format_function.call(-1234.123456, 0))
    assertEqual('-12,345', format_function.call(-12345.123456, 0))
    assertEqual('-123,456', format_function.call(-123456.123456, 0))
    assertEqual('-1,234,567', format_function.call(-1234567.123456, 0))
    assertEqual('-12,345,678', format_function.call(-12345678.123456, 0))
    assertEqual('-123,456,789', format_function.call(-123456789.123456, 0))
    // thousands separator and decimal
    assertEqual('1,234.12', format_function.call(1234.123456, 2))
    assertEqual('12,345.12', format_function.call(12345.123456, 2))
    assertEqual('123,456.12', format_function.call(123456.123456, 2))
    assertEqual('1,234,567.12', format_function.call(1234567.123456, 2))
    assertEqual('12,345,678.12', format_function.call(12345678.123456, 2))
    assertEqual('123,456,789.12', format_function.call(123456789.123456, 2))
    assertEqual('-1,234.12', format_function.call(-1234.123456, 2))
    assertEqual('-12,345.12', format_function.call(-12345.123456, 2))
    assertEqual('-123,456.12', format_function.call(-123456.123456, 2))
    assertEqual('-1,234,567.12', format_function.call(-1234567.123456, 2))
    assertEqual('-12,345,678.12', format_function.call(-12345678.123456, 2))
    assertEqual('-123,456,789.12', format_function.call(-123456789.123456, 2))
}

console.log('======== Testing ========');
test(Number.prototype.format);
test(Number.prototype.format1);
test(Number.prototype.format2);
test(Number.prototype.format3);

Benchmark

function benchmark(f) {
    var start = new Date().getTime();
    f();
    return new Date().getTime() - start;
}

function benchmark_format(f) {
    console.log(f);
    time = benchmark(function () {
        for (var i = 0; i < 100000; i++) {
            f.call(123456789, 0);
            f.call(123456789, 2);
        }
    });
    console.log(time.format(0) + 'ms');
}

// if not using async, browser will stop responding while running.
// this will create a new thread to benchmark
async = [];
function next() {
    setTimeout(function () {
        f = async.shift();
        f && f();
        next();
    }, 10);
}

console.log('======== Benchmark ========');
async.push(function () { benchmark_format(Number.prototype.format); });
next();