Indian Rupee (INR) - comma separator

inr-comma-separator.js

function formatNumber(numberToFormat) {
  // converting to string
  numberToFormat = numberToFormat + '' || '';
  // to make it works for integer and floating as well
  var numberAndDecimal = numberToFormat.split('.');
  // decimals points only
  var decimals = numberAndDecimal[1] || null;
  // add commas 
  numberAndDecimal = numberAndDecimal[0].replace(/(\d)(?=(\d\d)+\d$)/g, "$1,");
  // join 
  numberToFormat = decimals ? numberAndDecimal + '.' + decimals : numberAndDecimal;
  // return formatted
  return numberToFormat;
}

alert(formatNumber(prompt("Enter Number", 1234567.89)));