code: function startRoll(state) {
          var rolls = document.getElementsByClassName('roll');
          rolls[0].className = 'roll animate';
          rolls[1].className = 'roll animate';
          rolls[2].className = 'roll animate';
          setTimeout(() => stopRoll(state), 5000);
      }
docs: @description 抽奖动画开始
  @param {*} state
  
  因为动画是css控制所以结束时间大致用了setTimeout，没做精准的判断