GM_xmlhttpRequest如何正确处理EUC-JP编码显示日文？

const ab2str = (arraybuf, encodetype) => {
    var decoder = new textdecoder(encodetype);
    var u8arr = new uint8array(arraybuf);
    return decoder.decode(u8arr);
};

GM_xmlhttpRequest({
        method: "GET",
        url: "https://seesaawiki.jp/av_video/d/%c6%e1%b2%ec%ba%ea%a4%e6%a4%ad%a4%cd",
        responseType: "arraybuffer", // Get response as ArrayBuffer
        onload: function(response) {
            if (response.status >= 200 && response.status < 300) {
                // Convert ArrayBuffer to EUC-JP string
                const eucJpString = ab2str(response.response, 'EUC-JP');

                // Do something with the EUC-JP string
                console.log(eucJpString);
            } else {
                console.error("Error fetching data:", response.status);
            }
        },
        onerror: function(error) {
            console.error("Request error:", error);
        },
    });