This requires two operations...

1. Parse the number string into a Number instance

   const actualNumber = +number.replace(/,/g, '') // produces 4500.02734
   

2. Format the string to a given locale with a maximum of 2 decimal places

   const formatted = actualNumber.toLocaleString('en-US', {maximumFractionDigits: 2})
   

var number = '4,500.02734'

const actualNumber = +number.replace(/,/g, '')
const formatted = actualNumber.toLocaleString('en-US', {maximumFractionDigits: 2})

document.write(formatted)

Did you add the locale to the toLocaleString function? for example javascript var number = 12345.543; number.toLocaleString('en') if i print the above code in the console it shows "12,345.543"

@cane van caneYou can limit it via regex and JavaScript combination. Eliminate the ‘,’ input and limit number from 2-10 along with decimal places (below code limits to 2 digits after decimal). If the input doesn’t match regex it would clear the text box. Add below code in Question JavaScript section.Qualtrics.SurveyEngine.addOnload(function() { var inputElement = jQuery("#" + this.questionId + " .InputText"); inputElement.on("blur", function() { var inputValue = jQuery(this).val(); // Regex for valid number format (2-9.99 or 10) var numberPattern = /^((10)|(2-9?))$/; if (!numberPattern.test(inputValue)) { // Invalid input jQuery(this).val(""); // Clear the input field or handle as needed } });});Hope it helps!Happy Holidays

You could accomplish this by splitting your string at the '.' character and then performing your comma-conversion on the first section only, as such:

function ReplaceNumberWithCommas(yourNumber) {
    //Seperates the components of the number
    var n= yourNumber.toString().split(".");
    //Comma-fies the first part
    n[0] = n[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    //Combines the two sections
    return n.join(".");
}

ReplaceNumberWithCommas(1136.6696); //yields 1,136.6696

Example

If you're doing this to several fields, or doing it quite often, then perhaps a plugin is the answer.
Here's the beginnings of a jQuery plugin that formats the value of a field to two decimal places.
It is triggered by the onchange event of the field. You may want something different.

<script type="text/javascript">

    // mini jQuery plugin that formats to two decimal places
    (function($) {
        $.fn.currencyFormat = function() {
            this.each( function( i ) {
                $(this).change( function( e ){
                    if( isNaN( parseFloat( this.value ) ) ) return;
                    this.value = parseFloat(this.value).toFixed(2);
                });
            });
            return this; //for chaining
        }
    })( jQuery );

    // apply the currencyFormat behaviour to elements with 'currency' as their class
    $( function() {
        $('.currency').currencyFormat();
    });

</script>   
<input type="text" name="one" class="currency"><br>
<input type="text" name="two" class="currency">

Works on all browsers, this is all you need.

  function commaSeparateNumber(val){
    while (/(\d+)(\d{3})/.test(val.toString())){
      val = val.toString().replace(/(\d+)(\d{3})/, '$1'+','+'$2');
    }
    return val;
  }

Wrote this to be compact, and to the point, thanks to regex. This is straight JS, but you can use it in your jQuery like so:

$('#elementID').html(commaSeparateNumber(1234567890));

or

$('#inputID').val(commaSeparateNumber(1234567890));

However, if you require something cleaner, with flexibility. The below code will fix decimals correctly, remove leading zeros, and can be used limitlessly. Thanks to @baacke in the comments.

  function commaSeparateNumber(val){
   val = val.toString().replace(/,/g, ''); //remove existing commas first
   var valRZ = val.replace(/^0+/, ''); //remove leading zeros, optional
   var valSplit = valRZ.split('.'); //then separate decimals
    
   while (/(\d+)(\d{3})/.test(valSplit[0].toString())){
    valSplit[0] = valSplit[0].toString().replace(/(\d+)(\d{3})/, '$1'+','+'$2');
   }

   if(valSplit.length == 2){ //if there were decimals
    val = valSplit[0] + "." + valSplit[1]; //add decimals back
   }else{
    val = valSplit[0]; }

   return val;
  }

And in your jQuery, use like so:

$('.your-element').each(function(){
  $(this).html(commaSeparateNumber($(this).html()));
});

Here's the jsFiddle.

$(this).temp1() looks particularly out of place, I think you just meant to use the temp1 variable. Since it's already a number, you don't need to use parseFloat on it either:

$("#discount").change(function() {
    var list = $("#list").val();
    var discount = $("#discount").val();
    var price = $("#price");
    var temp = discount * list;
    var temp1 = list - temp;
    var total = temp1.toFixed(2);

    price.val(total);
});

Could do this, but what I would do instead is show the comma separated number elsewhere besides the input field.

$('input.number').keyup(function(event) {

  // skip for arrow keys
  if(event.which >= 37 && event.which <= 40){
   event.preventDefault();
  }

  $(this).val(function(index, value) {
      value = value.replace(/,/g,''); // remove commas from existing input
      return numberWithCommas(value); // add commas back in
  });
});

function numberWithCommas(x) {
    var parts = x.toString().split(".");
    parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    return parts.join(".");
}

http://jsfiddle.net/jpAmE/