type ReportHandler = (metric: any) => void; const reportWebVitals = (onPerfEntry?: ReportHandler): void => { if (onPerfEntry && typeof onPerfEntry === "function") { import("web-vitals") .then((wv: any) => { const { getCLS, getFID, getFCP, getLCP, getTTFB } = wv as any; if (typeof getCLS === "function") getCLS(onPerfEntry); if (typeof getFID === "function") getFID(onPerfEntry); if (typeof getFCP === "function") getFCP(onPerfEntry); if (typeof getLCP === "function") getLCP(onPerfEntry); if (typeof getTTFB === "function") getTTFB(onPerfEntry); }) .catch(() => { // optional: swallow import errors in environments where web-vitals isn't available }); } }; export default reportWebVitals;