js amount thousandth place retains 3 decimal places, if it is insufficient, make up 0

function number_format(number, decimals, dec_point, thousands_sep) {
            /*
            * Parameter description:
            * number: the number to format
            * decimals: several decimal places
            * dec_point: decimal symbol
            * thousands_sep: thousands symbol
            * */
            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.ceil(n * k) / k;
                };
         
            s = (prec ? toFixedFix(n, prec) : '' + Math.round(n)).split('.');
            var re = /(-?\d+)(\d{3})/;
            while (re.test(s[0])) {
                s[0] = s[0].replace(re, "$1" + sep + "$2");
            }
         
            if ((s[1] || '').length < prec) {
                s[1] = s[1] || '';
                s[1] += new Array(prec - s[1].length + 1).join('0');
            }
            return s.join(dec);
        }

 

Instructions:

1   var num=number_format(1234567.0891, 3, ".", ",");//1,234,567.089