How do I format numbers using JavaScript?

问题:

I want to format numbers using JavaScript.

For example:

10     => 10.00
100    => 100.00
1000   => 1,000.00
10000  => 10,000.00
100000 => 100,000.00

回答1:

If you want to use built-in code, you can use toLocaleString() with minimumFractionDigits, although browser compatibility for the extended options on toLocaleString() is limited.

var n = 100000;
var value = n.toLocaleString(
  undefined, // leave undefined to use the browser\'s locale,
             // or use a string like \'en-US\' to override it.
  { minimumFractionDigits: 2 }
);
console.log(value);
// In en-US, logs \'100,000.00\'
// In de-DE, logs \'100.000,00\'
// In hi-IN, logs \'1,00,000.00\'

If you\'re using Node.js, you will need to npm install the intl package.

回答2:

Short solution:

var n = 1234567890;
String(n).replace(/(.)(?=(\\d{3})+$)/g,\'$1,\')
// \"1,234,567,890\"

回答3:

Use

num = num.toFixed(2);

Where 2 is the number of decimal places

Edit:

Here\'s the function to format number as you want

function formatNumber(number)
{
    number = number.toFixed(2) + \'\';
    x = number.split(\'.\');
    x1 = x[0];
    x2 = x.length > 1 ? \'.\' + x[1] : \'\';
    var rgx = /(\\d+)(\\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, \'$1\' + \',\' + \'$2\');
    }
    return x1 + x2;
}

Sorce: www.mredkj.com

回答4:

Due to the bugs found by JasperV — good points! — I have rewritten my old code. I guess I only ever used this for positive values with two decimal places.

Depending on what you are trying to achieve, you may want rounding or not, so here are two versions split across that divide.

First up, with rounding.

I\'ve introduced the toFixed() method as it better handles rounding to specific decimal places accurately and is well support. It does slow things down however.

This version still detaches the decimal, but using a different method than before. The w|0 part removes the decimal. For more information on that, this is a good answer. This then leaves the remaining integer, stores it in k and then subtracts it again from the original number, leaving the decimal by itself.

Also, if we\'re to take negative numbers into account, we need to while loop (skipping three digits) until we hit b. This has been calculated to be 1 when dealing with negative numbers to avoid putting something like -,100.00

The rest of the loop is the same as before.

function formatThousandsWithRounding(n, dp){
  var w = n.toFixed(dp), k = w|0, b = n < 0 ? 1 : 0,
      u = Math.abs(w-k), d = (\'\'+u.toFixed(dp)).substr(2, dp),
      s = \'\'+k, i = s.length, r = \'\';
  while ( (i-=3) > b ) { r = \',\' + s.substr(i, 3) + r; }
  return s.substr(0, i + 3) + r + (d ? \'.\'+d: \'\');
};

In the snippet below you can edit the numbers to test yourself.

function formatThousandsWithRounding(n, dp){
  var w = n.toFixed(dp), k = w|0, b = n < 0 ? 1 : 0,
      u = Math.abs(w-k), d = (\'\'+u.toFixed(dp)).substr(2, dp),
      s = \'\'+k, i = s.length, r = \'\';
  while ( (i-=3) > b ) { r = \',\' + s.substr(i, 3) + r; }
  return s.substr(0, i + 3) + r + (d ? \'.\'+d: \'\');
};

var dp;
var createInput = function(v){
  var inp = jQuery(\'<input class=\"input\" />\').val(v);
  var eql = jQuery(\'<span>&nbsp;=&nbsp;</span>\');
  var out = jQuery(\'<div class=\"output\" />\').css(\'display\', \'inline-block\');
  var row = jQuery(\'<div class=\"row\" />\');
  row.append(inp).append(eql).append(out);
  inp.keyup(function(){
    out.text(formatThousandsWithRounding(Number(inp.val()), Number(dp.val())));
  });
  inp.keyup();
  jQuery(\'body\').append(row);
  return inp;
};

jQuery(function(){
  var numbers = [
    0, 99.999, -1000, -1000000, 1000000.42, -1000000.57, -1000000.999
  ], inputs = $();
  dp = jQuery(\'#dp\');
  for ( var i=0; i<numbers.length; i++ ) {
    inputs = inputs.add(createInput(numbers[i]));
  }
  dp.on(\'input change\', function(){
    inputs.keyup();
  });
});

<script src=\"https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js\"></script>
<input id=\"dp\" type=\"range\" min=\"0\" max=\"5\" step=\"1\" value=\"2\" title=\"number of decimal places?\" />

Now the other version, without rounding.

This takes a different route and attempts to avoid mathematical calculation (as this can introduce rounding, or rounding errors). If you don\'t want rounding, then you are only dealing with things as a string i.e. 1000.999 converted to two decimal places will only ever be 1000.99 and not 1001.00.

This method avoids using .split() and RegExp() however, both of which are very slow in comparison. And whilst I learned something new from Michael\'s answer about toLocaleString, I also was surprised to learn that it is — by quite a way — the slowest method out of them all (at least in Firefox and Chrome; Mac OSX).

Using lastIndexOf() we find the possibly existent decimal point, and from there everything else is pretty much the same. Save for the padding with extra 0s where needed. This code is limited to 5 decimal places. Out of my test this was the faster method.

var formatThousandsNoRounding = function(n, dp){
  var e = \'\', s = e+n, l = s.length, b = n < 0 ? 1 : 0,
      i = s.lastIndexOf(\'.\'), j = i == -1 ? l : i,
      r = e, d = s.substr(j+1, dp);
  while ( (j-=3) > b ) { r = \',\' + s.substr(j, 3) + r; }
  return s.substr(0, j + 3) + r + 
    (dp ? \'.\' + d + ( d.length < dp ? 
        (\'00000\').substr(0, dp - d.length):e):e);
};

var formatThousandsNoRounding = function(n, dp){
  var e = \'\', s = e+n, l = s.length, b = n < 0 ? 1 : 0,
      i = s.lastIndexOf(\'.\'), j = i == -1 ? l : i,
      r = e, d = s.substr(j+1, dp);
  while ( (j-=3) > b ) { r = \',\' + s.substr(j, 3) + r; }
  return s.substr(0, j + 3) + r + 
  	(dp ? \'.\' + d + ( d.length < dp ? 
    	(\'00000\').substr(0, dp - d.length):e):e);
};

var dp;
var createInput = function(v){
  var inp = jQuery(\'<input class=\"input\" />\').val(v);
  var eql = jQuery(\'<span>&nbsp;=&nbsp;</span>\');
  var out = jQuery(\'<div class=\"output\" />\').css(\'display\', \'inline-block\');
  var row = jQuery(\'<div class=\"row\" />\');
  row.append(inp).append(eql).append(out);
  inp.keyup(function(){
    out.text(formatThousandsNoRounding(Number(inp.val()), Number(dp.val())));
  });
  inp.keyup();
  jQuery(\'body\').append(row);
  return inp;
};

jQuery(function(){
  var numbers = [
    0, 99.999, -1000, -1000000, 1000000.42, -1000000.57, -1000000.999
  ], inputs = $();
  dp = jQuery(\'#dp\');
  for ( var i=0; i<numbers.length; i++ ) {
    inputs = inputs.add(createInput(numbers[i]));
  }
  dp.on(\'input change\', function(){
    inputs.keyup();
  });
});

<script src=\"https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js\"></script>
<input id=\"dp\" type=\"range\" min=\"0\" max=\"5\" step=\"1\" value=\"2\" title=\"number of decimal places?\" />

I\'ll update with an in-page snippet demo shortly, but for now here is a fiddle:

https://jsfiddle.net/bv2ort0a/2/

Old Method

Why use RegExp for this? — don\'t use a hammer when a toothpick will do i.e. use string manipulation:

var formatThousands = function(n, dp){
  var s = \'\'+(Math.floor(n)), d = n % 1, i = s.length, r = \'\';
  while ( (i -= 3) > 0 ) { r = \',\' + s.substr(i, 3) + r; }
  return s.substr(0, i + 3) + r + 
    (d ? \'.\' + Math.round(d * Math.pow(10, dp || 2)) : \'\');
};

walk through

formatThousands( 1000000.42 );

First strip off decimal:

s = \'1000000\', d = ~ 0.42

Work backwards from the end of the string:

\',\' + \'000\'
\',\' + \'000\' + \',000\'

Finalise by adding the leftover prefix and the decimal suffix (with rounding to dp no. decimal points):

\'1\' + \',000,000\' + \'.42\'

fiddlesticks

http://jsfiddle.net/XC3sS/

回答5:

On browsers that support the ECMAScript® 2016 Internationalization API Specification (ECMA-402), you can use an Intl.NumberFormat instance:

var nf = Intl.NumberFormat();
var x = 42000000;
console.log(nf.format(x)); // 42,000,000 in many locales
                           // 42.000.000 in many other locales

if (typeof Intl === \"undefined\" || !Intl.NumberFormat) {
  console.log(\"This browser doesn\'t support Intl.NumberFormat\");
} else {
  var nf = Intl.NumberFormat();
  var x = 42000000;
  console.log(nf.format(x)); // 42,000,000 in many locales
                             // 42.000.000 in many other locales
}

回答6:

I think with this jQuery-numberformatter you could solve your problem.

$(\"#salary\").blur(function(){
   $(this).parseNumber({format:\"#,###.00\", locale:\"us\"});
   $(this).formatNumber({format:\"#,###.00\", locale:\"us\"});
});

Of course, this is assuming that you don\'t have problem with using jQuery in your project.

回答7:

Use the Number function toFixed and this function to add the commas.

function addCommas(nStr)
{
    nStr += \'\';
    var x = nStr.split(\'.\');
    var x1 = x[0];
    var x2 = x.length > 1 ? \'.\' + x[1] : \'\';
    var rgx = /(\\d+)(\\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, \'$1\' + \',\' + \'$2\');
    }
    return x1 + x2;
}
n = 10000;
r = n.toFixed(2); //10000.00

addCommas(r); // 10,000.00

http://www.mredkj.com/javascript/numberFormat.html

回答8:

function numberWithCommas(x) {
  x=String(x).toString();
  var afterPoint = \'\';
  if(x.indexOf(\'.\') > 0)
     afterPoint = x.substring(x.indexOf(\'.\'),x.length);
  x = Math.floor(x);
  x=x.toString();
  var lastThree = x.substring(x.length-3);
  var otherNumbers = x.substring(0,x.length-3);
  if(otherNumbers != \'\')
      lastThree = \',\' + lastThree;
  return otherNumbers.replace(/\\B(?=(\\d{2})+(?!\\d))/g, \",\") + lastThree + afterPoint;
}

console.log(numberWithCommas(100000));
console.log(numberWithCommas(10000000));

Output

1,00,000
1,00,00,000

回答9:

This is an article about your problem. Adding a thousands-seperator is not built in to JavaScript, so you\'ll have to write your own function like this (example taken from the linked page):

function addSeperator(nStr){
  nStr += \'\';
  x = nStr.split(\'.\');
  x1 = x[0];
  x2 = x.length > 1 ? \'.\' + x[1] : \'\';
  var rgx = /(\\d+)(\\d{3})/;
  while (rgx.test(x1)) {
    x1 = x1.replace(rgx, \'$1\' + \',\' + \'$2\');
  }
  return x1 + x2;
}

回答10:

Or you could use the sugar.js library, and the format method:

format( place = 0 , thousands = \',\' , decimal = \'.\' ) Formats the number to a readable string. If place is undefined, will automatically determine the place. thousands is the character used for the thousands separator. decimal is the character used for the decimal point.

Examples:

(56782).format() > \"56,782\"
(56782).format(2) > \"56,782.00\"
(4388.43).format(2, \' \') > \"4 388.43\"
(4388.43).format(3, \'.\', \',\') > \"4.388,430\"

回答11:

If you are looking for a formatting with limit to three significant digits, for example:

1,23,45,67,890.123

Use:

number.toLocaleString(\'en-IN\');

Working Example:

let number = 1234567890.123; 

document.write(number.toLocaleString(\'en-IN\'));

Tested in Chrome v60.0.3112.113

Source: Number.prototype.toLocaleString() | MDN

回答12:

This will get you your comma seperated values as well as add the fixed notation to the end.

    nStr=\"1000\";
    nStr += \'\';
    x = nStr.split(\'.\');
    x1 = x[0];
    x2 = x.length > 1 ? \'.\' + x[1] : \'\';
    var rgx = /(\\d+)(\\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, \'$1\' + \',\' + \'$2\');
    }
    commaSeperated = x1 + x2 + \".00\";
    alert(commaSeperated);

Source

回答13:

Let me also throw my solution in here. I\'ve commented each line for ease of reading and also provided some examples, so it may look big.

function format(number) {

    var decimalSeparator = \".\";
    var thousandSeparator = \",\";

    // make sure we have a string
    var result = String(number);

    // split the number in the integer and decimals, if any
    var parts = result.split(decimalSeparator);

    // if we don\'t have decimals, add .00
    if (!parts[1]) {
      parts[1] = \"00\";
    }
  
    // reverse the string (1719 becomes 9171)
    result = parts[0].split(\"\").reverse().join(\"\");

    // add thousand separator each 3 characters, except at the end of the string
    result = result.replace(/(\\d{3}(?!$))/g, \"$1\" + thousandSeparator);

    // reverse back the integer and replace the original integer
    parts[0] = result.split(\"\").reverse().join(\"\");

    // recombine integer with decimals
    return parts.join(decimalSeparator);
}

document.write(\"10 => \" + format(10) + \"<br/>\");
document.write(\"100 => \" + format(100) + \"<br/>\");
document.write(\"1000 => \" + format(1000) + \"<br/>\");
document.write(\"10000 => \" + format(10000) + \"<br/>\");
document.write(\"100000 => \" + format(100000) + \"<br/>\");
document.write(\"100000.22 => \" + format(100000.22) + \"<br/>\");

回答14:

If you\'re using jQuery, you could use the format or number format plugins.

回答15:

 function formatNumber1(number) {
  var comma = \',\',
      string = Math.max(0, number).toFixed(0),
      length = string.length,
      end = /^\\d{4,}$/.test(string) ? length % 3 : 0;
  return (end ? string.slice(0, end) + comma : \'\') + string.slice(end).replace(/(\\d{3})(?=\\d)/g, \'$1\' + comma);
 }

 function formatNumber2(number) {
  return Math.max(0, number).toFixed(0).replace(/(?=(?:\\d{3})+$)(?!^)/g, \',\');
 }

Source: http://jsperf.com/number-format

回答16:

This is about 3 times faster version of the accepted answer. It doesn\'t create array and avoids object creation and string concatenation for whole numbers at the end. This might be useful if you render lots of values e.g. in a table.

function addThousandSeparators(number) {
    var whole, fraction
    var decIndex = number.lastIndexOf(\'.\')
    if (decIndex > 0) {
        whole = number.substr(0, decIndex)
        fraction = number.substr(decIndex)
    } else {
        whole = number
    }
    var rgx = /(\\d+)(\\d{3})/
    while (rgx.test(whole)) {
        whole = whole.replace(rgx, \'$1\' + \',\' + \'$2\')
    }
    return fraction ? whole + fraction : whole
}