preemptive-animation-frame/Readme.md

Preemptive requestAnimationFrame

# preemptive-animation-frame
[![travis][travis-image]][travis-url]
[![npm][npm-image]][npm-url]
[![downloads][downloads-image]][downloads-url]
[![js-standard-style][standard-image]][standard-url]

Library provides same API as [window.requestAnimationFrame][] but in contrast it is preemptive. It is possible to drop a frame if [window.requestAnimationFrame][] is called *(after you've done handling of the current frame)* too late. This library helps you avoid such frames drops by wrapping native API and scheduling request ahead of time.

It is especially useful when working with high level abstractions that require you to schedule requests at the end update step.

## Install

```bash
npm install preemptive-animation-frame
```

## API

```js
const PAF = require('preemptive-animation-frame')

// schedule
const requestID = PAF.requestAnimationFrame(time => {
  // repaint
})

// cancel
PAF.cancelAnimationFrame(requestID)
```

## Unstable API

You can force animation frame to fire at your demand with `forceAnimationFrame`

```js
PAF.forceAnimationFrame()
```

Library internally uses [`performance.now()`][performance-now] polyfill, if you use it in conjunction with this library consider using exported `now` function to have consistent starting point for produced timestamps.

```js
PAF.now()
```

[window.requestAnimationFrame]:https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame
[travis-image]: https://travis-ci.org/Gozala/preemptive-animation-frame.svg?branch=master
[travis-url]: https://travis-ci.org/Gozala/preemptive-animation-frame
[npm-image]: https://img.shields.io/npm/v/preemptive-animation-frame.svg
[npm-url]: https://npmjs.org/package/preemptive-animation-frame
[downloads-image]: https://img.shields.io/npm/dm/preemptive-animation-frame.svg
[downloads-url]: https://npmjs.org/package/preemptive-animation-frame
[standard-image]:https://img.shields.io/badge/code%20style-standard-brightgreen.svg
[standard-url]:http://standardjs.com/
[performance-now]:https://www.npmjs.com/package/performance-now