2021年1月16日

今日はMoshiさんの講座を聞きます.

function Stopwatch() {
  let startTime, endTime, running, duration = 0;
  
  this.strat = function() {
    if(running) 
      throw new Error('Stopwatch has already started.')
    
    running = true;

    startTIme = new Date();

  };

  this.stop = function () {
    if(!running)
      throw new Error('Stopwtch is not started.');
    
    running = false;

    endTime = new Date();

    const seconds =(endTime.getTime() - startTime.getTime()) / 1000;
    duration += seconds;

  };

  this.reset = function() {
    startTime = null;
    endTime = null;
    running = false;
    duration = 0;
  };

  Object.defineProperty(this, 'duration', {
    get: function() { return duration; }

  });
}

これは何ですか.ダンスパーティーと同じですか?
https://developer.mozilla.org/ko/docs/Web/API/EventTarget/addEventListener
https://developer.mozilla.org/en-US/docs/Web/Events\
setTimeout

.back--img {
  position: absolute;
  z-index: -1;
  opacity: 70%;
}