Is Math.ceil() & Math.round() supported on IE8?

I have a Javascript function that calculates a value and re-inserts the value into a <td> while also injecting the value into a hidden <input>.

This is my function:

$("input[name^='policies']:checkbox").change(function() {
    var el = $(this);

    if (el.is(":checked")) {
        no_policies++;
    }

    if (el.is(":not(:checked)")) {
        no_policies--;
    }

    subscription = no_policies*policy_cost;
    first_payment = Math.ceil(subscription+no_policies*(policy_cost/days_month)*days_left).toFixed(2);

    alert(first_payment);

    $("td#first_payment").text("R "+first_payment);
    $("input#first_payment_txt").val(first_payment);
    $("td#subscr开发者_C百科iption").text("R "+subscription.toFixed(2));    
});

Everything works on IE8 up until this statement:

first_payment = Math.ceil(subscription+no_policies*(policy_cost/days_month)*days_left).toFixed(2);

I suspect IE8 is having trouble with Math.ceil, is that true? Also, is there any other function/method I can use to circumvent this?

Thanks in advance.

Answer is yes to both your questions:

Math.ceil()

Math.round()

Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards.

See also general table of Javascript compatibility for different IE versions:

Seems like microsoft supports Math.ceil on all versions beginning from ie6 (msdn), maybe one of the variables use is undefined or you devide by 0 or one of the variables is not a number so the result cannot be ceiled/rounded.

IE8 actually has a fairly good debugger. I recommend hitting F12 to open it, then going to the Script tab and selecting the Start Debugging button. This will let you set breakpoints along the script, letting it stop and wait for you to analyze variables as it executes at your own pace. As Adriano mentions in his comment, it's most likely an issue with one of your variables.