3 Ways To Add Comma To Numbers In Javascript (Thousands Separator)

Welcome to a short tutorial on how to add commas to numbers in Javascript. So you have a project that needs to display some “nice-looking numbers”?

That covers the basics, but let us walk through more examples in this guide – Read on!

 

 

TLDR – QUICK SLIDES

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TABLE OF CONTENTS

 

 

 

METHOD 1) LOCALE STRING

// (A) THE NUMBER
var num = 1234567.89;
 
// (B) TO LOCALE STRING
console.log(num.toLocaleString("en-US")); // 1,234,567.89
console.log(num.toLocaleString("fr-FR")); // 1 234 567,89
console.log(num.toLocaleString("ja-JP", { style: "currency", currency: "JPY" }));

As in the introduction, toLocaleString("en-US") is one of the easiest ways to add commas to a number. For beginners, that en-US fr-FR ja-JP is the language and locale code.

• The language code is 2 alphabets ISO 639-1. Check out Wikipedia for the full list.
• The locale code is ISO 3166-1 alpha-2. Check out Wikipedia for the complete list.

P.S. I have another tutorial to format the number as a currency, link below.

 

 

METHOD 2) REGULAR EXPRESSION REPLACE

// CREDIT: https://stackoverflow.com/questions/2901102/how-to-print-a-number-with-commas-as-thousands-separators-in-javascript
// (A) THE NUMBER 
var num = 1234567.89;
 
// (B) CONVERT TO STRING & REPLACE
var commas = num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
console.log(commas); // 1,234,567.89

Once upon a time in the Dark Ages of the Internet, this is how we roll. Basically, convert the number into a string, then use a pattern (regular expression) to insert the commas. Not going into the details of how regular expression work, as it is a can of worms. But replace(/\B(?=(\d{3})+(?!\d))/g, ",") does the magic of inserting the commas.

 

 

METHOD 3) MANUAL INSERT COMMA

// (A) ADD COMMAS TO SEPERATE GIVEN NUMBER
// num : original number
// per : add comma per n digits (default 3)
// places : number of decimal places (default 2)
function addComma (num, per, places) {
  // (A1) SET DEFAULTS
  if (per==undefined) { per = 3; }
  if (places==undefined) { places = 2; }

  // (A2) NO DECIMAL PLACES - ROUND OFF
  // REMOVE THIS IF YOU DON'T WANT TO ROUND OFF
  if (places==0) { num = Math.round(num); }
 
  // (A3) SPLIT WHOLE & DECIMAL NUMBERS
  var cString = num.toString(),
      cDot = cString.indexOf("."),
      cWhole = "", cDec = "";
  if (cDot == -1) {
    cWhole = cString;
    cDec = 0;
  } else {
    cWhole = cString.substring(0, cDot);
    cDec = cString.substring(cDot+1);
  }
 
  // (A4) ADD COMMAS TO WHOLE NUMBER
  var aComma = "", count = 0;
  if (cWhole.length > per) { for (let i=(cWhole.length-1); i>=0; i--) {
    aComma = cWhole.charAt(i) + aComma;
    count++;
    if (count == per && i!=0) {
      aComma = "," + aComma; 
      count = 0;
    }
  }} else { aComma = cWhole; }
 
  // (A5) ROUND OFF TO GIVEN DECIMAL PLACES
  if (places==0) { cDec = ""; }
  else {
    cDec = +("0." + cDec);
    cDec = cDec.toFixed(places).toString().substring(1);
  }
 
  // (A6) RETURN "WHOLE WITH COMMA" PLUS DECIMAL PLACES
  return aComma + cDec;
}
 
// (B) TEST
// (B1) WHOLE NUMBER
var whole = 123456789;
console.log(addComma(whole)); // 123,456,789.00
console.log(addComma(whole, 4, 0)); // 1,2345,6789

// (B2) DECIMAL
var dec = 23456.78;
console.log(addComma(dec)); // 23,456.78
console.log(addComma(dec, 2, 0)); // 2,34,57

Lastly, this is another manual alternative to adding commas to a number –

• (A1) The “default settings” if none are provided.
• (A2) Round off if 0 decimal places. Remove this line if you don’t want to round off.
• (A3) Convert the number into a string, split it into the whole numbers and decimals.
• (A4) Only add commas to the portion of the whole number.
• (A5) Round off to the given number of decimal places.
• (A6) Combine the whole and decimals back – Done!

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

SUMMARY

Function	Description	Link
NUMBER.toLocaleString()	Format the number to the specified locale.	Click Here
NUMBER.toString()	Converts a number to a string.	Click Here
STRING.replace()	Replace all instances of a matched pattern in the string.	Click Here

 

LINKS & REFERENCES

• Format Number As Currency In Javascript – Code Boxx

 

TUTORIAL VIDEO

 

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