JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<head>
  <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"/>
  <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"></script>
  <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script>


</head>
<body style="font-size:62.5%;">
  <input type="text" id="amount" style="border:0; color:#f6931f; font-weight:bold;" />

<div id="slider"></div>

</body>
</html>

CSS

#slider { margin: 10px; }

JavaScript

function number_format(number, decimals, dec_point, thousands_sep) {
    number = (number + '').replace(/[^0-9+\-Ee.]/g, '');
    var n = !isFinite(+number) ? 0 : +number,
        prec = !isFinite(+decimals) ? 0 : Math.abs(decimals),
        sep = (typeof thousands_sep === 'undefined') ? ',' : thousands_sep,
        dec = (typeof dec_point === 'undefined') ? '.' : dec_point,
        s = '',
        toFixedFix = function (n, prec) {
            var k = Math.pow(10, prec);
            return '' + Math.round(n * k) / k;
        };
    // Fix for IE parseFloat(0.55).toFixed(0) = 0;
    s = (prec ? toFixedFix(n, prec) : '' + Math.round(n)).split('.');
    if (s[0].length > 3) {
        s[0] = s[0].replace(/\B(?=(?:\d{3})+(?!\d))/g, sep);
    }
    if ((s[1] || '').length < prec) {
        s[1] = s[1] || '';
        s[1] += new Array(prec - s[1].length + 1).join('0');
    }
    return s.join(dec);
}

$(function() {
         $( "#slider" ).slider({
             value:100,
             min: 0,
             max: 5000000000,
             step: 1,
             slide: function( event, ui ) {
                 $( "#amount" ).val( "£" + number_format(ui.value, 2, '.', ',') );
             }
         });
         $( "#amount" ).val( "£" + $( "#slider" ).slider( "value" ) );
     });