function GetAgeInYearsFromDOB(year, month, day) {
    var now = new Date()
    var dob = new Date(parseInt(year), parseInt(month) - 1, parseInt(day));

    var ms = now.getTime() - dob.getTime();
    var minutes = ms / 1000 / 60;
    var hours = minutes / 60;
    var days = hours / 24;
    var years = days / 365.25;

    return Math.floor(years);
}

String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g, "");
}


String.prototype.toTwoDecimalPlaces = function() {
    return Math.round(this * 100) / 100;
}

String.prototype.isValidPostcode = function() {

    toCheck = this;
    // Permitted letters depend upon their position in the postcode.
    var alpha1 = "[abcdefghijklmnoprstuwyz]";                       // Character 1
    var alpha2 = "[abcdefghklmnopqrstuvwxy]";                       // Character 2
    var alpha3 = "[abcdefghjkstuw]";                                // Character 3
    var alpha4 = "[abehmnprvwxy]";                                  // Character 4
    var alpha5 = "[abdefghjlnpqrstuwxyz]";                          // Character 5

    // Array holds the regular expressions for the valid postcodes
    var pcexp = new Array();

    // Expression for postcodes: AN NAA, ANN NAA, AAN NAA, and AANN NAA
    pcexp.push(new RegExp("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1,2})(\\s*)([0-9]{1}" + alpha5 + "{2})$", "i"));

    // Expression for postcodes: ANA NAA
    pcexp.push(new RegExp("^(" + alpha1 + "{1}[0-9]{1}" + alpha3 + "{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$", "i"));

    // Expression for postcodes: AANA  NAA
    pcexp.push(new RegExp("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1}" + alpha4 + "{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$", "i"));

    // Exception for the special postcode GIR 0AA
    pcexp.push(/^(GIR)(\s*)(0AA)$/i);

    // Standard BFPO numbers
    pcexp.push(/^(bfpo)(\s*)([0-9]{1,4})$/i);

    // c/o BFPO numbers
    pcexp.push(/^(bfpo)(\s*)(c\/o\s*[0-9]{1,3})$/i);

    // Overseas Territories
    pcexp.push(/^([A-Z]{4})(\s*)(1ZZ)$/i);

    // Load up the string to check
    var postCode = toCheck;

    // Assume we're not going to find a valid postcode
    var valid = false;

    // Check the string against the types of post codes
    for (var i = 0; i < pcexp.length; i++) {
        if (pcexp[i].test(postCode)) {

            // The post code is valid - split the post code into component parts
            pcexp[i].exec(postCode);

            // Copy it back into the original string, converting it to uppercase and
            // inserting a space between the inward and outward codes
            postCode = RegExp.$1.toUpperCase() + " " + RegExp.$3.toUpperCase();

            // If it is a BFPO c/o type postcode, tidy up the "c/o" part
            postCode = postCode.replace(/C\/O\s*/, "c/o ");

            // Load new postcode back into the form element
            valid = true;

            // Remember that we have found that the code is valid and break from loop
            break;
        }
    }

    // Return with either the reformatted valid postcode or the original invalid 
    // postcode
    if (valid) {
        return true;
    }
    else {
        return false;
    }
}

/*
Get value of selected radio button group
http://johndyer.name/post/2006/08/Get-the-value-of-a-radio-button-in-JavaScript.aspx
*/
function getRadioValue(idOrName) {
    var value = null;
    var element = document.getElementById(idOrName);
    var radioGroupName = null;

    // if null, then the id must be the radio group name
    if (element == null) {
        radioGroupName = idOrName;
    } else {
        radioGroupName = element.name;
    }
    if (radioGroupName == null) {
        return null;
    }
    var radios = document.getElementsByTagName('input');
    for (var i = 0; i < radios.length; i++) {
        var input = radios[i];
        if (input.type == 'radio' && input.name == radioGroupName && input.checked) {
            value = input.value;
            break;
        }
    }
    return value;
}