CSS 动画事件
事件名称 何时触发animationstart 某个 CSS 动画开始时触发。
animationend 某个 CSS 动画完成时触发。
animationiteration 某个 CSS 动画完成后重新开始时触发。
CSS 过渡事件
事件名称 何时触发transitionstart A
CSS transition has actually started (fired after any delay).
transitioncancel CSS过渡被取消
transitionend CSS过渡已经完成
transitionrun A
CSS transition has begun running (fired before any delay starts).