cra-template-doly/template/src/reportWebVitals.ts

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type ReportHandler = (...args: unknown[]) => void;

const reportWebVitals = (onPerfEntry?: ReportHandler) => {
  if (onPerfEntry && onPerfEntry instanceof Function) {
    import('web-vitals').then(({ onCLS, onINP, onFCP, onLCP, onTTFB }) => {
      onCLS(onPerfEntry);
      onINP(onPerfEntry);
      onFCP(onPerfEntry);
      onLCP(onPerfEntry);
      onTTFB(onPerfEntry);
    });
  }
};

export default reportWebVitals;