net_hook.js

(() => {
  try {
    const FLAG = "__JM_SLOW_CRAWLER_NET_MONITOR__";
    if (window[FLAG]) return;
    window[FLAG] = true;

    const normUrl = (u) => {
      try {
        return new URL(String(u || ""), location.href).href;
      } catch {
        return String(u || "");
      }
    };

    const report = (rec) => {
      try {
        window.postMessage({ __jmSlowCrawler: true, type: "net_error", rec }, "*");
      } catch {}
    };

    // fetch
    try {
      const origFetch = window.fetch;
      if (typeof origFetch === "function") {
        window.fetch = function (input, init) {
          let url = "";
          let method = "GET";
          try {
            url =
              typeof input === "string"
                ? input
                : input && input.url
                ? input.url
                : "";
            method = (init && init.method) || (input && input.method) || "GET";
          } catch {}
          const absUrl = normUrl(url);
          const m = String(method || "GET").toUpperCase();

          return origFetch
            .apply(this, arguments)
            .then((res) => {
              try {
                const st = res && typeof res.status === "number" ? res.status : 0;
                if (st >= 400 && absUrl.includes("/thread/")) {
                  report({ time: Date.now(), url: absUrl, status: st, method: m });
                }
              } catch {}
              return res;
            })
            .catch((err) => {
              try {
                if (absUrl.includes("/thread/")) {
                  report({
                    time: Date.now(),
                    url: absUrl,
                    status: 0,
                    method: m,
                    err: String(err),
                  });
                }
              } catch {}
              throw err;
            });
        };
      }
    } catch {}

    // XHR
    try {
      const origOpen = XMLHttpRequest.prototype.open;
      const origSend = XMLHttpRequest.prototype.send;

      XMLHttpRequest.prototype.open = function (method, url) {
        try {
          this.__jm_method = method;
          this.__jm_url = url;
        } catch {}
        return origOpen.apply(this, arguments);
      };

      XMLHttpRequest.prototype.send = function () {
        try {
          this.addEventListener(
            "loadend",
            () => {
              try {
                const abs = normUrl(this.__jm_url || "");
                const st = typeof this.status === "number" ? this.status : 0;
                const m = String(this.__jm_method || "GET").toUpperCase();
                if (st >= 400 && abs.includes("/thread/")) {
                  report({ time: Date.now(), url: abs, status: st, method: m });
                }
              } catch {}
            },
            { once: true }
          );
        } catch {}
        return origSend.apply(this, arguments);
      };
    } catch {}
  } catch {}
})();