fps

fps.js

function detectFpsInPeriod(options) {
  const now = () => performance.now()
  const startTime = now()
  let lastOutputTime = now();
  let frameCount = 0;
  const fpsResult = []

  let stoped = false;

  function getFps() {
    frameCount++;
    let currentFrame = now()

    if (currentFrame - lastOutputTime >= 1000) {
      const fps = frameCount
      fpsResult.push({
        fps
      })
      frameCount = 0;
      lastOutputTime = currentFrame;
    }


    if (!stoped) {
      requestAnimationFrame(getFps)
    }
  }

  setTimeout(() => {
    options.callback && options.callback(fpsResult, startTime, now())
    stoped = true
  }, options.seconds * 1000);

  requestAnimationFrame(getFps)
}

function autoScrollInSeconds(seconds) {
  const now = () => performance.now()
  const element = document.querySelector('#_current_nested_child')
  const startTime = now()
  const endTime = startTime + seconds * 1000
  
  function scrollDown() {
    element.scrollTop += 8

    if (now() < endTime) {
      requestAnimationFrame(scrollDown)
    }
  }
  
  requestAnimationFrame(scrollDown)
}

var seconds = 240

detectFpsInPeriod({
  seconds: seconds,
  callback: (result, startTime, endTime) => {
    console.log(JSON.stringify(result))
    // console.log('FPS TimeInfo', startTime, endTime)
  },
  frequency: 250
})

autoScrollInSeconds(seconds)