@react-spring/rafz

Coordinate requestAnimationFrame calls across your app and/or libraries.

• < 700 bytes min+gzip
• Timeout support
• Batching support (eg: ReactDOM.unstable_batchedUpdates)
• Uncaught errors are isolated
• Runs continuously (to reduce frame skips)

API

import { raf } from 'rafz'

// Schedule an update
raf(dt => {})

// Start an update loop
raf(dt => true)

// Cancel an update
raf.cancel(fn)

// Schedule a mutation
raf.write(() => {})

// Before any updates
raf.onStart(() => {})

// Before any mutations
raf.onFrame(() => {})

// After any mutations
raf.onFinish(() => {})

// Set a timeout that runs on nearest frame
raf.setTimeout(() => {}, 1000)

// Use a polyfill
raf.use(require('@essentials/raf').raf)

// Get the current time
raf.now() // => number

// Set how you want to control raf firing
raf.frameLoop = 'demand' | 'always'

Notes

• Functions can only be scheduled once per queue per frame.
• Thus, trying to schedule a function twice is a no-op.
• The update phase is for updating JS state (eg: advancing an animation).
• The write phase is for updating native state (eg: mutating the DOM).
• Reading is allowed any time before the write phase.
• Writing is allowed any time after the onFrame phase.
• Timeout handlers run first on each frame.
• Any handler (except timeouts) can return true to run again next frame.
• The raf.cancel function only works with raf handlers.
• Use raf.sync to disable scheduling in its callback.
• Override raf.batchedUpdates to avoid excessive re-rendering in React.

raf.throttle

Wrap a function to limit its execution to once per frame. If called more than once in a single frame, the last arguments are used.

let log = raf.throttle(console.log)

log(1)
log(2) // nothing logged yet

raf.onStart(() => {
  // "2" is logged by now
})

// Cancel a pending call.
log.cancel()

// Access the wrapped function.
log.handler

Prior art

• fastdom
• framesync