web-fps-caculate.js

const rAF = function() {
  return window.requestAnimationFrame ||
          window.webkitRequestAnimationFrame ||
          function (cb) {
            window.setTimeout(cb, 1000 / 60);
          }
}();

let frame = 0
let lastTime = Date.now();

function loop () {
  const now = Date.now();
  frame += 1
  if (now > 1000 + lastTime) {
    const fps = Math.round((frame * 1000) / (now - lastTime))
    console.log(`${new Date()} 1S内 FPS：`, fps);
    frame = 0
    lastTime = now
  }
  rAF(loop)
}
loop()