// JavaScript Document
//Simple checks
var myCost = 7.50;
var myPostage = 0;
var myAmount = 1;
function formatDecimal(argvalue, addzero, decimaln) {
  var numOfDecimal = (decimaln == null) ? 2 : decimaln;
  var number = 1;

  number = Math.pow(10, numOfDecimal);

  argvalue = Math.round(parseFloat(argvalue) * number) / number;
  // If you're using IE3.x, you will get error with the following line.
  // argvalue = argvalue.toString();
  // It works fine in IE4.
  argvalue = "" + argvalue;

  if (argvalue.indexOf(".") == 0)
    argvalue = "0" + argvalue;

  if (addzero == true) {
    if (argvalue.indexOf(".") == -1)
      argvalue = argvalue + ".";

    while ((argvalue.indexOf(".") + 1) > (argvalue.length - numOfDecimal))
      argvalue = argvalue + "0";
  }

  return argvalue;
}


function addPostage()
{
myPostage = (window.document.myForm.myNumber.value*window.document.myForm.postageZone.value);
myAmount = (window.document.myForm.myNumber.value*myCost);
window.document.myForm.myPostage.value = formatDecimal(myPostage,true,2);
window.document.myForm.myAmount.value = myAmount;
window.document.myForm.amount.value = formatDecimal(myAmount+myPostage,true,2);
}

function isInt() {
	var isNumeric = window.document.myForm.myNumber.value;
	if (isNumeric == "" || isNumeric<"1") { 
		alert("Minimum order is 1 copy");
		window.document.myForm.myNumber.value="1";
		addPostage();
		return false;
	}
	if(isNumeric >=parseInt("6"))
	{
	alert("Sorry the maximum number ordered online is 5 copies.\n If you require more please see the contact page for more information")
	window.document.myForm.myNumber.value="5";
		addPostage();
		return false;
	}
	for (var i = 0; i < isNumeric.length; i++) {
		if (isNumeric.charAt(i) < "0" || isNumeric.charAt(i) > "9") {
			alert("Numeric values only please");
			window.document.myForm.myNumber.value="1";
			addPostage();
			return false;
		}
	}
	addPostage();
	return true;
}