String.prototype.getQuery = function(name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");
    var r = this.substr(this.indexOf("\?") + 1).match(reg);
    if (r != null) return unescape(r[2]); return null;
}

function getCookie(cname) {
    if (document.cookie.length > 0) {
        var cstart = document.cookie.indexOf(cname + "=")
        if (cstart != -1) {
            cstart = cstart + cname.length + 1
            var cend = document.cookie.indexOf(";", cstart)
            if (cend == -1)
                cend = document.cookie.length
            return unescape(document.cookie.substring(cstart, cend))
        }
    }
    else
        return "";
}

function setCookie(cname, value) {
    var expires = new Date();
    expires.setTime(expires.getTime() + 24 * 60 * 60 * 1000);
    document.cookie = cname + "=" + escape(value) + ";path=/;expires=" + expires.toGMTString();

}

function setEtag() {
    var url = window.location.href;
    var etag = url.getQuery("etag");
    if (etag != null)
    {
            var cookie_date = new Date ( );  // current date & time
    cookie_date.setTime ( cookie_date.getTime() - 1 );
    document.cookie = "etag=;" + " " + "expires=" + cookie_date.toGMTString();
    setCookie("etag", etag);
    }
}
    

function getEtag() {
    var etagstr = getCookie("etag");
    if(etagstr == undefined)
        return "";
    else 
        return etagstr;
}

setEtag();