var default_date = "12/18/2008"
    // default to show if server doesn't provide date
var lm = document.lastModified
    // server-provided date

if (Date.parse) {
    if (Date.parse(lm) == 0 || Date.parse(lm) == '' || Date.parse(lm) == null) {
    lm = default_date
    }

    document.write("Last Modified on: " + lm)
}