动画：persist() 方法

persist()

<div id="animation-target"></div>
<button id="start-persistent">Add persistent animation</button>
<button id="start-transient">Add transient animation</button>
<button id="cancel">Cancel an animation</button>
<ol id="stack"></ol>

<template id="list-item-template">
  <li>
    <span class="replaceState"></span>,
    <span class="description"></span>
  </li>
</template>

div {
  width: 100px;
  height: 100px;
  background: red;
  transform: translate(100px);
}

const target = document.getElementById("animation-target");
const persistentButton = document.getElementById("start-persistent");
const transientButton = document.getElementById("start-transient");
const cancelButton = document.getElementById("cancel");
persistentButton.addEventListener("click", () => startAnimation(true));
transientButton.addEventListener("click", () => startAnimation(false));
cancelButton.addEventListener("click", cancelTop);
const stack = [];

let offset = -100;

function startAnimation(persist) {
  offset = -offset;
  const animation = target.animate(
    { transform: `translate(${100 + offset}px)` },
    { duration: 500, fill: "forwards" },
  );
  stack.push(animation);
  if (persist) {
    animation.persist();
  }
  // Add the animation to the displayed stack (implementation not shown)
  show(animation, offset);
}

function cancelTop() {
  stack.pop()?.cancel();
}

const stackDisplay = document.getElementById("stack");
const template =
  document.getElementById("list-item-template").content.firstElementChild;
const nodes = new Map();

function show(animation, offset) {
  const direction = offset < 0 ? "left" : "right";
  const li = template.cloneNode(true);
  const description = li.querySelector(".description");
  const replaceState = li.querySelector(".replaceState");
  description.textContent = direction;
  replaceState.textContent = animation.replaceState;
  nodes.set(animation, { li, description, replaceState });
  stackDisplay.append(li);
  animation.addEventListener("cancel", () => {
    nodes.get(animation).li.remove();
    nodes.delete(animation);
  });
  animation.addEventListener("remove", () => {
    nodes.get(animation).replaceState.textContent = animation.replaceState;
  });
}