这节我用的 opacity动画实现的
css:

.ace-enter-active,
.ace-leave-active {
  transition:
    height 0.2s ease-in-out,
    opacity 0.2s ease-in-out;
}

js:

const transitionEvents: Record<string, (el: HTMLElement) => void> = {
  beforeEnter(el) {
    el.style.height = '0px';
    el.style.opacity = '0';
  },
  enter(el) {
    el.style.height = `${el.scrollHeight}px`;
    el.style.opacity = '1';
  },
  afterEnter(el) {
    el.style.height = '';
    el.style.opacity = '';
  },
  beforeLeave(el) {
    el.style.height = `${el.scrollHeight}px`;
    el.style.opacity = '1';
  },
  leave(el) {
    el.style.height = '0px';
    el.style.opacity = '0';
  },
  afterLeave(el) {
    el.style.height = '';
    el.style.opacity = '';
  },
};