// The following JavaScript is needed to assist with
    // the usability of the Age Verification form on this page

    function textboxFocus(box, defaultText) {
        if (box.value == defaultText) {
            // blank out the box so its ready to accept a number
            box.value = '';
        }
        else {
            // highlight the value so its ready to accept a number
            box.select();
        }
    }
    function textboxBlur(box, defaultText) {
        if (box.value != defaultText) {
            if (box.value == '') {
                // textbox is blank
                box.value = defaultText;
            }
            else {
                // textbox is not blank
                if (box.value.length == 1) {
                    // textbox value is less than 10 and needs a leading zero
                    box.value = '0' + box.value;
                }
                if (box.value < 0) {
                    // textbox value is a negative number, so change it to a positive number
                    box.value = box.value * -1;
                }
            }
        }
    }
    function moveCursor(box) {
        if (box.value.length > 1) {
            if (box == txtMonth)
                txtDay.focus();
            if (box == txtDay)
                txtYear.focus();
            if (box == txtYear)
                btnVerifyAge.focus();
        }
    }
    function validateEntry(box, event) {
        if (isEditingKey(event)) {
            return true;
        }
        else {
            // only allow digits
            if (!isNumberKey(event))
                return false;
        }
        moveCursor(box);
        return true;
    }
    function isNumberKey(event) {
        // only allow charCodes of 48-57 (digits 0-9)
        var charCode = (event.which) ? event.which : event.keyCode
        if ((charCode >= 48 && charCode <= 57)
                    || (charCode >= 96 && charCode <= 105))
            return true;

        return false;
    }
    function isEditingKey(event) {
        // only allow the following charCodes
        // 8 = backspace
        // 9 = tab
        // 46 = delete
        // 37 = left
        // 38 = up
        // 39 = right
        // 40 = down
        var charCode = (event.which) ? event.which : event.keyCode
        if ((charCode >= 37 && charCode <= 40)
                    || charCode == 8
                    || charCode == 9
                    || charCode == 46)
            return true;

        return false;
    }
    function validateDate() {
        var month = txtMonth.value;
        var day = txtDay.value
        var year = '19' + txtYear.value;
        var dateString = month + '/' + day + "/" + year;
        return isDate(dateString);
    }
    /**
    * DHTML date validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
    */
    // Declaring valid date character, minimum year and maximum year
    var dtCh = "/";
    var minYear = 1900;
    var maxYear = 2100;

    function isInteger(s) {
        var i;
        for (i = 0; i < s.length; i++) {
            // Check that current character is number.
            var c = s.charAt(i);
            if (((c < "0") || (c > "9"))) return false;
        }
        // All characters are numbers.
        return true;
    }

    function stripCharsInBag(s, bag) {
        var i;
        var returnString = "";
        // Search through string's characters one by one.
        // If character is not in bag, append to returnString.
        for (i = 0; i < s.length; i++) {
            var c = s.charAt(i);
            if (bag.indexOf(c) == -1) returnString += c;
        }
        return returnString;
    }

    function daysInFebruary(year) {
        // February has 29 days in any year evenly divisible by four,
        // EXCEPT for centurial years which are not also divisible by 400.
        return (((year % 4 == 0) && ((!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28);
    }
    function DaysArray(n) {
        for (var i = 1; i <= n; i++) {
            this[i] = 31
            if (i == 4 || i == 6 || i == 9 || i == 11) { this[i] = 30 }
            if (i == 2) { this[i] = 29 }
        }
        return this
    }

    function isDate(dtStr) {
        var daysInMonth = DaysArray(12)
        var pos1 = dtStr.indexOf(dtCh)
        var pos2 = dtStr.indexOf(dtCh, pos1 + 1)
        var strMonth = dtStr.substring(0, pos1)
        var strDay = dtStr.substring(pos1 + 1, pos2)
        var strYear = dtStr.substring(pos2 + 1)
        strYr = strYear
        if (strDay.charAt(0) == "0" && strDay.length > 1) strDay = strDay.substring(1)
        if (strMonth.charAt(0) == "0" && strMonth.length > 1) strMonth = strMonth.substring(1)
        for (var i = 1; i <= 3; i++) {
            if (strYr.charAt(0) == "0" && strYr.length > 1) strYr = strYr.substring(1)
        }
        month = parseInt(strMonth)
        day = parseInt(strDay)
        year = parseInt(strYr)
        if (pos1 == -1 || pos2 == -1) {
            alert("The date format should be : mm/dd/yyyy");
            return false;
        }
        if (strMonth.length < 1 || month < 1 || month > 12) {
            alert("Please enter a valid month");
            txtMonth.focus();
            return false;
        }
        if (strDay.length < 1 || day < 1 || day > 31 || (month == 2 && day > daysInFebruary(year)) || day > daysInMonth[month]) {
            alert("Please enter a valid day");
            txtDay.focus();
            return false;
        }
        if (strYear.length != 4 || year == 0 || year < minYear || year > maxYear) {
            alert("Please enter a valid 4 digit year between " + minYear + " and " + maxYear);
            txtYear.focus();
            return false;
        }
        if (dtStr.indexOf(dtCh, pos2 + 1) != -1 || isInteger(stripCharsInBag(dtStr, dtCh)) == false) {
            alert("Please enter a valid date");
            txtMonth.focus();
            return false;
        }
        return true
    }