FPS計測したいとき

fps_calculator.js

    class FpsCalculator {
      constructor() {
        this._isRunning = false;
        this._beginTime = Date.now();
        this._prevTime = this._beginTime;
        this._frames = 0;
      }
      start() {
        if (this._isRunning) {
          return null;
        }

        this._beginTime = Date.now();
        this._prevTime = this._beginTime;
        this._frames = 0;

        this._isRunning = true;
        const loop = () => {
          if (!this._isRunning) {
            return null;
          }
          this._update();
          requestAnimationFrame(loop);
        }
        loop();
      }
      stop() {
        this._isRunning = false;
        this._frames = 0;
      }
      _update() {
        this._frames++;
        let prevTime = this._prevTime;
        let time = Date.now();

        if (time > prevTime + 1000) {
          console.log((this._frames * 1000) / (time - prevTime));
          this._prevTime = time;
          this._frames = 0;
        }

        this._beginTime = time;
      }
    }
    const calculator = new FpsCalculator();
    calculator.start();