Format numbers in JavaScript similar to C#

Question

Is there a simple way to format numbers in JavaScript, similar to the formatting methods available in C# (or VB.NET) via ToString(\"format_provider\") or

Answer 1

Yes, there is definitely a way to format numbers properly in javascript, for example:

var val=2489.8237

val.toFixed(3) //returns 2489.824 (round up)
val.toFixed(2) //returns 2489.82
val.toFixed(7) //returns 2489.8237000 (padding)

With the use of variablename.toFixed .

And there is another function toPrecision() . For more detail you also can visit

http://raovishal.blogspot.com/2012/01/number-format-in-javascript.html

Answer 2

If you don't want to use jQuery, take a look at Numeral.js

Answer 3

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.format1 === 'undefined') {
    Number.prototype.format1 = 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.format2 === 'undefined') {
    Number.prototype.format2 = 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.format3 === 'undefined') {
    Number.prototype.format3 = 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('');
    };
}

Example

console.log('======== Demo ========')
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');
}

async = [];
function next() {
    setTimeout(function () {
        f = async.shift();
        f && f();
        next();
    }, 10);
}

console.log('======== Benchmark ========');
async.push(function () { benchmark_format(Number.prototype.format); });
async.push(function () { benchmark_format(Number.prototype.format1); });
async.push(function () { benchmark_format(Number.prototype.format2); });
async.push(function () { benchmark_format(Number.prototype.format3); });
next();

Answer 4

http://code.google.com/p/javascript-number-formatter/ :

• Short, fast, flexible yet standalone. Only 75 lines including MIT license info, blank lines & comments.
• Accept standard number formatting like #,##0.00 or with negation -000.####.
• Accept any country format like # ##0,00, #,###.##, #'###.## or any type of non-numbering symbol.
• Accept any numbers of digit grouping. #,##,#0.000 or #,###0.## are all valid.
• Accept any redundant/fool-proof formatting. ##,###,##.# or 0#,#00#.###0# are all OK.
• Auto number rounding.
• Simple interface, just supply mask & value like this: format( "0.0000", 3.141592)

UPDATE

As say Tomáš Zato here one line solution:

(666.0).toLocaleString()
numObj.toLocaleString([locales [, options]])

which described in ECMA-262 5.1 Edition:

• http://www.ecma-international.org/ecma-262/5.1/#sec-15.7.4.3
• https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString

and will work in future versions of browsers...

Answer 5

Here's another version:

$.fn.digits = function () {
    return this.each(function () {
        var value = $(this).text();
        var decimal = "";
        if (value) {
            var pos = value.indexOf(".");
            if (pos >= 0) {
                decimal = value.substring(pos);
                value = value.substring(0, pos);
            }
            if (value) {
                value = value.replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
                if (!String.isNullOrEmpty(decimal)) value = (value + decimal);
                $(this).text(value);
            }
        }
        else {
            value = $(this).val()
            if (value) {
                var pos = value.indexOf(".");
                if (pos >= 0) {
                    decimal = value.substring(pos);
                    value = value.substring(0, pos);
                }
                if (value) {
                    value = value.replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
                    if (!String.isNullOrEmpty(decimal)) value = (value + decimal);
                    $(this).val(value);
                }
            }
        }
    })
};

Answer 6

Generally

• Formatting numbers in JavaScript
• Formatting numbers for currency display and more.

In jQuery

• autoNumeric (a decent number formatter & input helper with locale support for jQuery 1.5+)
• jQuery Format (a clientSide implementation of Java's SimpleDateFormat and NumberFormat)
• jquery-numberformatter (number formatter with locale support)