prebid / Prebid.js / 17815574309

coverage: 96.24% (-0.002%) from 96.242%

Source File
Press 'n' to go to next uncovered line, 'b' for previous

66.67
/libraries/timeToFirstBytesUtils/timeToFirstBytesUtils.js
1 
/**
2 
 * Calculates the Time to First Byte (TTFB) for the given window object.
3 
 *
4 
 * This function attempts to use the Navigation Timing Level 2 API first, and falls back to
5 
 * the Navigation Timing Level 1 API if the former is not available.
6 
 *
7 
 * @param {Window} win - The window object from which to retrieve performance timing information.
8 
 * @returns {string} The TTFB in milliseconds as a string, or an empty string if the TTFB cannot be determined.
9 
 */
10 
export function getTimeToFirstByte(win) {
11 
  const performance = win.performance || win.webkitPerformance || win.msPerformance || win.mozPerformance;
66!
12 









13



  const ttfbWithTimingV2 = performance &&





66✔





14



        typeof performance.getEntriesByType === 'function' &&










15



        Object.prototype.toString.call(performance.getEntriesByType) === '[object Function]' &&










16



        performance.getEntriesByType('navigation')[0] &&










17



        performance.getEntriesByType('navigation')[0].responseStart &&










18



        performance.getEntriesByType('navigation')[0].requestStart &&










19



        performance.getEntriesByType('navigation')[0].responseStart > 0 &&










20



        performance.getEntriesByType('navigation')[0].requestStart > 0 &&










21



        Math.round(










22



          performance.getEntriesByType('navigation')[0].responseStart - performance.getEntriesByType('navigation')[0].requestStart










23



        );










24












25



  if (ttfbWithTimingV2) {





66✔





26



    return ttfbWithTimingV2.toString();




66✔





27



  }










28












29



  const ttfbWithTimingV1 = performance &&





×







30



        performance.timing.responseStart &&










31



        performance.timing.requestStart &&










32



        performance.timing.responseStart > 0 &&










33



        performance.timing.requestStart > 0 &&










34



        performance.timing.responseStart - performance.timing.requestStart;










35












36



  return ttfbWithTimingV1 ? ttfbWithTimingV1.toString() : '';





×







37



}
























    

  • 

    •