Convert JavaScript to C#

Question

How to convert this JavaScript to C#?

<script>
  function zeroPad(num, places) {
    var zero = places - num.toString().length + 1;
    return Array(+(zero > 0 && zero)).join("0") + num;
  }

    var accum = 0;
    var pin = parseInt(form.mac.value.replace(/:/g, '').slice(-6), 16) % 12000;
    var p = pin;
    while (pin)
      accum = (((accum + (3 * (pin % 10))) | 0) + (((pin / 10) | 0) % 10)) | 0, pin = ((pin / 100) | 0);
    accum = ((10 - accum % 10) % 10);
    form.pin.value = (zeroPad(p, 7) + "" + accum);
  }
</script>

Please explain me this line in details?

parseInt(form.mac.value.replace(/:/g, '').slice(-6), 16) % 12000;

Answer 1

I believe start-to-finish code conversions are a bit out of scope of Stack Overflow. If you posted your non-working C# conversion attempt and asked where it went wrong, I'm sure you'd get a much quicker answer to your first question.

As for your second question:

parseInt(form.mac.value.replace(/:/g, '').slice(-6), 16) % 12000;

translates to:

// Gets some mac address from some object outside the code you posted
var MACAddrString = form.mac.value;
// Delete the :'s between MAC address bytes
MACAddrString = MACAddrString.replace(/:/g, '');
// Take the last 3 bytes (6 hex digit symbols)
MACAddrString = MACAddrString.slice(-6);
// Parse the hex string to a number. Second argument indicates base 16.
var MACAddrInt = parseInt(MACAddrString, 16);
// Calculate the pin
var pin = MACAddrInt % 12000;

Answer 2

 $(document).ready(function () { StartCountDown(); }); //start the countdown

function Decrement() {
    currentMinutes = Math.floor(secs / 60);
    currentSeconds = secs % 60;
    if (currentSeconds <= 9) currentSeconds = "0" + currentSeconds;
    secs--;
    document.getElementById("timerText").innerHTML = "Time Remaining " + currentMinutes + ":" + currentSeconds;
    if (secs !== -1) {
        setTimeout('Decrement()', 1000);
    }
    else {
        window.location.href = "default.aspx?timeout=1"
    }
}

function CheckIfAllQuestionAnswerHasBeenSubmitted() {
    var numItems = $('.tblOptions').length;
    var flagtocheckcount = 0;
    $(".tblOptions").each(function () {
        var groupname = $('input[type=radio]:first', this).attr('name');
        if (!$("input[name='" + groupname + "']:checked").val()) {
            $(this).parents(".tableclass").addClass("border");
            var tableid = $(this).closest('table [class^="tableclass"]').attr("id");
        }
        else {
            flagtocheckcount = flagtocheckcount + 1;
        }
    })

Answer 3

Wrapping javascript function for access using c# instead of conversion/porting

You could look into using Jurassic for doing that.

Calling a JavaScript function from .NET