When rounding decimals, there are some built-in javascript functions that can help you with the basics
var num = 10; var result = num.toFixed(2); // result will equal 10.00 num = 930.9805; result = num.toFixed(3); // result will equal 930.981 num = 500.2349; result = num.toPrecision(4); // result will equal 500.2 num = 5000.2349; result = num.toPrecision(4); // result will equal 5000 num = 555.55; result = num.toPrecision(2); // result will equal 5.6e+2
Formatting with Commas
To add commas to a large number, there is no built in javascript function. The function below will add commas to a large number.
function formatNumber(nStr) { nStr += ''; x = nStr.split('.'); x1 = x[0]; x2 = x.length > 1 ? '.' + x[1] : ''; var rgx = /(d+)(d{3})/; while (rgx.test(x1)) { x1 = x1.replace(rgx, '$1' + ',' + '$2'); } return x1 + x2; }