function addCommasToNumber(number) {

  // Convert the number to a string

  const strNumber = number.toString();

​

  // Split the number into integer and decimal parts (if any)

  const parts = strNumber.split('.');

  const integerPart = parts[0];

  const decimalPart = parts[1] || '';

​

  // Add commas to the integer part

  const integerWithCommas = integerPart.replace(/\B(?=(\d{3})+(?!\d))/g, ',');

​

  // Combine the integer and decimal parts (if any) with commas

  const numberWithCommas = decimalPart ? `${integerWithCommas}.${decimalPart}` : integerWithCommas;

​

  return numberWithCommas;

}

​

// Example usage:

const number = 1234567.89;

const numberWithCommas = addCommasToNumber(number);

console.log(numberWithCommas);  // Output: "1,234,567.89"

function numberWithCommas(x) {

  return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');

}

var number = 1000;

    console.log(number.toLocaleString());

//output: 1,000

var n = 34523453.345

n.toLocaleString()

"34,523,453.345"

​

// A more complex example: 

number.toLocaleString(); // "1,234,567,890"

​

// A more complex example: 

var number2 = 1234.56789; // floating point example

number2.toLocaleString(undefined, {maximumFractionDigits:2}) // "1,234.57"

let n = 234234234;

let str = n.toLocaleString("en-US");

console.log(str); // "234,234,234"

var number = 3500;

​

console.log(number.toLocaleString());

var number = 3500;

​

console.log(new Intl.NumberFormat().format(number));

// → '3,500' if in US English locale

​

value.toLocaleString()

"1,000"

function numberWithCommas(x) {

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

}