Animation: replaceState property

A string that represents the replace state of the animation. The value can be one of:

active

The initial value of the animation's replace state; when the animation has been removed by the browser's Automatically removing filling animations behavior.

persisted

The animation has been explicitly persisted by invoking Animation.persist() on it.

removed

The animation has been explicitly removed.

In our simple replace indefinite animations demo, you can see the following code:

const divElem = document.querySelector("div");

document.body.addEventListener("mousemove", (evt) => {
  const anim = divElem.animate(
    { transform: `translate(${evt.clientX}px, ${evt.clientY}px)` },
    { duration: 500, fill: "forwards" }
  );

  anim.commitStyles();

  //anim.persist()

  anim.onremove = (event) => {
    console.log("Animation removed");
  };

  console.log(anim.replaceState);
});

Here we have a <div> element, and an event listener that fires the event handler code whenever the mouse moves. The event handler sets up an animation that animates the <div> element to the position of the mouse pointer. This could result in a huge animations list, which could create a memory leak. For this reason, modern browsers automatically remove overriding forward filling animations.

You can see the replaceState of the animation being logged at the end of the handler. This will be active for each animation by default, or persisted if the persist() call is uncommented.

• Web Animations API
• Animation