问题

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 String.Format()?

回答1:

You should probably have a look at the JQuery NUMBERFORMATTER plugin:

Jquery Number Formatter

And this question:

Javascript easier way to format numbers

回答2:

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)

回答3:

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

回答4:

Here's a simple JS function to add commas to an integer number in string format. It will handle whole numbers or decimal numbers. You can pass it either a number or a string. It obviously returns a string.

function addCommas(str) {
    var parts = (str + "").split("."),
        main = parts[0],
        len = main.length,
        output = "",
        first = main.charAt(0),
        i;

    if (first === '-') {
        main = main.slice(1);
        len = main.length;    
    } else {
        first = "";
    }
    i = len - 1;
    while(i >= 0) {
        output = main.charAt(i) + output;
        if ((len - i) % 3 === 0 && i > 0) {
            output = "," + output;
        }
        --i;
    }
    // put sign back
    output = first + output;
    // put decimal part back
    if (parts.length > 1) {
        output += "." + parts[1];
    }
    return output;
}

Here's a set of test cases: http://jsfiddle.net/jfriend00/6y57j/

You can see it being used in this previous jsFiddle: http://jsfiddle.net/jfriend00/sMnjT/. You can find functions that will handle decimal numbers too with a simple Google search for "javascript add commas".

Converting a number to a string can be done many ways. The easiest is just to add it to a string:

var myNumber = 3;
var myStr = "" + myNumber;   // "3"

Within, the context of your jsFiddle, you'd get commas into the counter by changing this line:

jTarget.text(current);

to this:

jTarget.text(addCommas(current));

You can see it working here: http://jsfiddle.net/jfriend00/CbjSX/

回答5:

I wrote a simple function (not yet another jQuery plugin needed!!) that converts a number to a decimal separated string or an empty string if the number wasn't a number to begin with:

function format(x) {
    return isNaN(x)?"":x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

format(578999); results in 578,999

format(10); results in 10

if you want to have a decimal point instead of a comma simply replace the comma in the code with a decimal point.

One of the comments correctly stated this only works for integers, with a few small adaptions you can make it work for floating points as well:

function format(x) {
    if(isNaN(x))return "";

    n= x.toString().split('.');
    return n[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",")+(n.length>1?"."+n[1]:"");
}

回答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.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();

回答7:

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

回答8:

Firstly, converting an integer into string in JS is really simple:

// Start off with a number
var number = 42;
// Convert into a string by appending an empty (or whatever you like as a string) to it
var string = 42+'';
// No extra conversion is needed, even though you could actually do
var alsoString = number.toString();

If you have a number as a string and want it to be turned to an integer, you have to use the parseInt(string) for integers and parseFloat(string) for floats. Both of these functions then return the desired integer/float. Example:

// Start off with a float as a string
var stringFloat = '3.14';
// And an int as a string
var stringInt = '42';

// typeof stringInt  would give you 'string'

// Get the real float from the string
var realFloat = parseFloat(someFloat);
// Same for the int
var realInt = parseInt(stringInt);

// but typeof realInt  will now give you 'number'

What exactly are you trying to append etc, remains unclear to me from your question.

回答9:

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...

回答10:

For example:

var flt = '5.99';
var nt = '6';

var rflt = parseFloat(flt);
var rnt = parseInt(nt);

回答11:

Using JQuery.

$(document).ready(function()
 {
    //Only number and one dot
    function onlyDecimal(element, decimals)
    {
        $(element).keypress(function(event)
        {
            num = $(this).val() ;
            num = isNaN(num) || num === '' || num === null ? 0.00 : num ;
            if ((event.which != 46 || $(this).val().indexOf('.') != -1) && (event.which < 48 || event.which > 57))
            {
                event.preventDefault();

            }
            if($(this).val() == parseFloat(num).toFixed(decimals))
            {
                event.preventDefault();
            }
        });
    }

     onlyDecimal("#TextBox1", 3) ;



});

回答12:

To get a decimal with 2 numbers after the comma, you could just use:

function nformat(a) {
   var b = parseInt(parseFloat(a)*100)/100;
   return b.toFixed(2);
}

回答13:

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);
                }
            }
        }
    })
};

回答14:

I made a simple function, maybe someone can use it

function secsToTime(secs){
  function format(number){
    if(number===0){
      return '00';
    }else {
      if (number < 10) {
          return '0' + number
      } else{
          return ''+number;
      }
    }
  }

  var minutes = Math.floor(secs/60)%60;
  var hours = Math.floor(secs/(60*60))%24;
  var days = Math.floor(secs/(60*60*24));
  var seconds = Math.floor(secs)%60;

  return (days>0? days+"d " : "")+format(hours)+':'+format(minutes)+':'+format(seconds);
}

this can generate the followings outputs:

5d 02:53:39
4d 22:15:16
03:01:05
00:00:00

回答15:

In case you want to format number for view rather than for calculation you can use this

function numberFormat( number ){

    var digitCount = (number+"").length;
    var formatedNumber = number+"";
    var ind = digitCount%3 || 3;
    var temparr = formatedNumber.split('');

    if( digitCount > 3 && digitCount <= 6 ){

        temparr.splice(ind,0,',');
        formatedNumber = temparr.join('');

    }else if (digitCount >= 7 && digitCount <= 15) {
        var temparr2 = temparr.slice(0, ind);
        temparr2.push(',');
        temparr2.push(temparr[ind]);
        temparr2.push(temparr[ind + 1]);
        // temparr2.push( temparr[ind + 2] ); 
        if (digitCount >= 7 && digitCount <= 9) {
            temparr2.push(" million");
        } else if (digitCount >= 10 && digitCount <= 12) {
            temparr2.push(" billion");
        } else if (digitCount >= 13 && digitCount <= 15) {
            temparr2.push(" trillion");

        }
        formatedNumber = temparr2.join('');
    }
    return formatedNumber;
}

Input: {Integer} Number

Outputs: {String} Number

22,870 => if number 22870

22,87 million => if number 2287xxxx (x can be whatever)

22,87 billion => if number 2287xxxxxxx

22,87 trillion => if number 2287xxxxxxxxxx

You get the idea

回答16:

To further jfriend00's answer (I dont't have enough points to comment) I have extended his/her answer to the following:

function log(args) {
    var str = "";
    for (var i = 0; i < arguments.length; i++) {
        if (typeof arguments[i] === "object") {
            str += JSON.stringify(arguments[i]);
        } else {
            str += arguments[i];
        }
    }
    var div = document.createElement("div");
    div.innerHTML = str;
    document.body.appendChild(div);
}

Number.prototype.addCommas = function (str) {
    if (str === undefined) {
    	str = this;
    }
    
    var parts = (str + "").split("."),
        main = parts[0],
        len = main.length,
        output = "",
        first = main.charAt(0),
        i;
    
    if (first === '-') {
        main = main.slice(1);
        len = main.length;    
    } else {
    	  first = "";
    }
    i = len - 1;
    while(i >= 0) {
        output = main.charAt(i) + output;
        if ((len - i) % 3 === 0 && i > 0) {
            output = "," + output;
        }
        --i;
    }
    // put sign back
    output = first + output;
    // put decimal part back
    if (parts.length > 1) {
        output += "." + parts[1];
    }
    return output;
}

var testCases = [
    1, 12, 123, -1234, 12345, 123456, -1234567, 12345678, 123456789,
    -1.1, 12.1, 123.1, 1234.1, -12345.1, -123456.1, -1234567.1, 12345678.1, 123456789.1
];
 
for (var i = 0; i < testCases.length; i++) {
	log(testCases[i].addCommas());
}
 
/*for (var i = 0; i < testCases.length; i++) {
    log(Number.addCommas(testCases[i]));
}*/

回答17:

May I suggest numbro for locale based formatting and number-format.js for the general case. A combination of the two depending on use-case may help.

来源：https://stackoverflow.com/questions/7124793/number-counting-up-needs-commas-decimal-point

标签

javascript

jquery

format

numbers

Format numbers in JavaScript similar to C#

问题