/* tests to see if string is in correct UK style postcode: AL1 1AB, BM1 5YZ etc. */
function isValidPostcode(p) {
        var postcodeRegEx = /[A-Z]{1,2}[0-9]{1,2} ?[0-9][A-Z]{2}/i;
        return postcodeRegEx.test(p);
}

/*        formats a VALID postcode nicely: AB120XY -> AB1 0XY */
function formatPostcode(p) {
        if (isValidPostcode(p)) {
                var postcodeRegEx = /(^[A-Z]{1,2}[0-9]{1,2})([0-9][A-Z]{2}$)/i;
                return p.replace(postcodeRegEx,"$1 $2");
        } else {
                return p;
        }
}