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docs(core): clarify null/undefined goals are skipped, not animated #2528

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joshuaellis merged 1 commit into from
Jun 9, 2026
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docs(core): clarify null/undefined goals are skipped, not animated #2528

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9 changes: 9 additions & 0 deletions docs/app/routes/docs.advanced.spring-value.mdx
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Expand Up @@ -27,6 +27,15 @@ Meanwhile you pass the `SpringValue` to your `animated` component. Any type is v
Types that cannot be animated are basically immediate: true animations. Such types include:
a `boolean`, a display string like `"none"`, etc.

> **`null` and `undefined` mean "leave this value alone".** They are not goals — a
> spring cannot animate _to_ `null`. When a key's value is `null`/`undefined` (or
> `false`) it is skipped, and the spring keeps whatever value it already holds. A key
> that has _only ever_ been `null`/`undefined` is never created at all.
>
> If you need to represent "no value", model it explicitly rather than relying on the
> spring to store `null` — for example keep the nullable state in React and feed the
> spring a real number (or toggle `immediate`/visibility) based on it.

```tsx
import { Component, createRef } from 'react'
import { SpringValue, animated } from '@react-spring/web'
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