JavaScript 處理 Cookie 的副程式

取得Cookie值

function GetCookieVal(offset){
    var endstr = document.cookie.indexOf (";", offset);
    if (endstr == -1) {
        endstr = document.cookie.length;
    }
    return unescape(document.cookie.substring(offset, endstr));
}

設定Cookie值

function SetCookie(name, value){
    var expdate = new Date();
    var argv = SetCookie.arguments;
    var argc = SetCookie.arguments.length;
    var expires = (argc > 2) ? argv[2] : null;
    var path = (argc > 3) ? argv[3] : null;
    var domain = (argc > 4) ? argv[4] : null;
    var secure = (argc > 5) ? argv[5] : false;
    if (expires!=null) {
        expdate.setTime(expdate.getTime() + ( expires * 1000 ));
    }
    document.cookie = name + "=" + escape (value) +((expires == null) ? "" : ("; expires="+ expdate.toGMTString()))
            +((path == null) ? "" : ("; path=" + path)) +((domain == null) ? "" : ("; domain=" + domain))
            +((secure == true) ? "; secure" : "");
}

刪除Cookie值

function DelCookie(name){
    var exp = new Date();
    exp.setTime (exp.getTime() - 1);
    var cval = GetCookie (name);
    document.cookie = name + "=" + cval + "; expires="+ exp.toGMTString();
}

取得未解碼Cookie值

function GetCookie(name){
    var arg = name + "=";
    var alen = arg.length;
    var clen = document.cookie.length;
    var i = 0;
    while (i < clen) {
        var j = i + alen;
        if (document.cookie.substring(i, j) == arg) {
            return GetCookieVal (j);
        }
        i = document.cookie.indexOf(" ", i) + 1;
        if (i == 0) {
            break;
        }
    }
    return null;
}