Format number in input box with comma

Insert comma input box for numbers in JavaScript

console.log(Number(monthly_income).toLocaleString());
console.log(Number(monthly_income).toLocaleString('en'));

toLocaleString is obselete 

https://syedabdulbaqi.wordpress.com/2009/03/10/javascript-function-for-converting-string-into-indian-currency-format/

   //function for converting string into indian currency format
    function intToFormat(nStr)
    {
     nStr += '';
     x = nStr.split('.');
     x1 = x[0];
     x2 = x.length > 1 ? '.' + x[1] : '';
     var rgx = /(\d+)(\d{3})/;
     var z = 0;
     var len = String(x1).length;
     var num = parseInt((len/2)-1);
 
      while (rgx.test(x1))
      {
        if(z > 0)
        {
          x1 = x1.replace(rgx, '$1' + ',' + '$2');
        }
        else
        {
          x1 = x1.replace(rgx, '$1' + ',' + '$2');
          rgx = /(\d+)(\d{2})/;
        }
        z++;
        num--;
        if(num == 0)
        {
          break;
        }
      }
     return x1 + x2;
    }