react-spring/docs/app/routes/docs.concepts.imperative-api.mdx

---
meta:
  title: Imperative API | React Spring
  'og:title': Imperative API | React Spring
  'twitter:title': Imperative API | React Spring
  description: An in-depth conceptual guide to Imperative API and what they are in React Spring.
  'og:description': An in-depth conceptual guide to Imperative API and what they are in React Spring.
  'twitter:description': An in-depth conceptual guide to Imperative API and what they are in React Spring.
  'og:url': https://www.react-spring.dev/docs/concepts/animated-elements
  'twitter:url': https://www.react-spring.dev/docs/concepts/animated-elements
sidebar_position: 3
---

import { formatFrontmatterToRemixMeta } from '../helpers/meta'

export const meta = formatFrontmatterToRemixMeta(frontmatter)

# Imperative API

The imperative API enables you to update your animations without requiring a react-render to occur. This is useful
for animations that are not tied to a component's lifecycle, such as animations that are triggered by user input.

In essence, it is simply a `SpringRef` with the hook's `Controller` attached to it. You can additionally add more `Controller`s
to the `SpringRef` to create a multi-controller animation, similar to that of the `useChain` hook.

## Comparison

What we can see from the below comparisons, is that using the `api` object either returned from your `useSpring` hook,
or generated via `useSpringRef` and passed to the hook, means your components do not re-render when the animation runs.

```tsx live=true template=imperative
import { useState } from 'react'
import { useSpring, useSpringRef, animated } from '@react-spring/web'

const ApiComponent = () => {
  const api = useSpringRef()
  const springs = useSpring({
    ref: api,
    from: { x: 0 },
  })

  const handleClick = () => {
    api.start({
      to: {
        x: springs.x.get() === 100 ? 0 : 100,
      },
    })
  }

  return (
    <div className="flex-container">
      <animated.div
        onClick={handleClick}
        style={{
          width: 80,
          height: 80,
          background: '#ff6d6d',
          borderRadius: 8,
          ...springs,
        }}
      />
      <span>Render ID – {Math.random()}</span>
    </div>
  )
}

const StateComponent = () => {
  const [forward, setForward] = useState(false)

  const springs = useSpring({
    x: forward ? 100 : 0,
  })

  const handleClick = () => {
    setForward(s => !s)
  }

  return (
    <div className="flex-container">
      <animated.div
        onClick={handleClick}
        style={{
          width: 80,
          height: 80,
          background: '#ff6d6d',
          borderRadius: 8,
          ...springs,
        }}
      />
      <span>Render ID – {Math.random()}</span>
    </div>
  )
}

export default function MyComponent() {
  return (
    <div className="flex-container--column">
      <ApiComponent />
      <StateComponent />
    </div>
  )
}
```

This way of working with react-spring lets you handle updates quicker and more effectively such as the position of the user's mouse.
It is the recommended approach for working with this library.

:::warning
When using a `SpringRef` or `api` return from a hook, any updates to the hook's configuration object are treated as `updates` and therefore
will not trigger the animation to run. You must call `.start()` to trigger the animation, thus flushing the update queue.
:::

## Methods

The entire list of methods & properties are visible [here](/docs/advanced/spring-ref). It's API signature is similar to both the [`Controller`](/docs/advanced/controller)
and [`SpringValue`](/docs/advanced/spring-value) class methods. This is done to create a single unified language across the library.

The most important methods you'll most likely use are [`start`](/docs/advanced/spring-ref#start) and [`set`](/docs/advanced/spring-ref#set).
However, if you are opting to use the `Controller` class manually as opposed to using our hooks/components, then you would have to manually
handle the lifecycle of adding/removing Controllers.

## Upgrading from v8

If you're upgrading from v8 of `react-spring`, then welcome! The imperative API is a new feature that has been added to v9. You're probably more
used to an api signature like this:

```ts
const [styles, set, stop] = useSpring(() => ({ x: 0 }))

set({
  x: 1,
})
```

This was okay for at the time, but as Controllers have become more powerful, it became clear that we needed a way a more scalable way to add methods
to the signature without extending the array too far.

The new api signature is like this:

```ts
const [styles, api] = useSpring(() => ({ x: 0 }))

api.start({
  x: 1,
})
```

:::note
We've used `start` in the above example demonstrating migration, this is because `set` acts like:

```ts
api.start({
  x: 1,
  immediate: true,
})
```

:::