react-sequencer v3.0.1
React Sequencer
A better way to do animations in React.
Links
Overview
Introduction
React sequencer lets you perform complex animations easily by tying them to a time-sequenced state machine. The simplest usage is to implement the useSequencer
hook inside your function components, which will give you the sequencer state and an api to control it.
You first define a set of steps for your sequence as tuples of names and durations:
const steps = [
['initial', 100],
['middle', 100],
['final', 0],
]
Then pass this as configuration to useSequencer:
import { useSequencer } from 'react-sequencer'
const steps = [
['initial', 100],
['middle', 100],
['final', 0],
]
const MyComponent = (props) => {
let [state, api] = useSequencer({ steps })
return (
<div>
<div>The current step: {state.current}</div>
<button
onClick={() => {
api.play()
}}
>
Start
</button>
</div>
)
}
Here state
contains the sequencer state and api
provides some methods to control the sequencer. When your sequencer starts playing, it runs through the steps and updates the state on every step, passing the current name
into state.current
.
Allowing you to control your time sequenced events in this way has many benefits:
- Easily add / remove or edit your steps from one place in your code
- Have your sequencer trigger css animations, text changes, or whatever you like
- Every step runs in its own animation frame so no repaint or timeout hacks are needed to get your animations behaving exactly as you like
- Add sequencers to multiple components and guarantee that they update in sync
Getting started
Install from NPM:
npm install react-sequencer
Documentation
useSequencer()
(options: Options) => [SequencerState, SequencerApi]
The useSequencer
hook is the recommended way to create a sequencer and inject its state into your component. It takes an options object as an argument.
options
options: Options
A configuration object to initialize the sequencer.
Returns
The hook returns a tuple of a SequencerState and SequencerApi.
Example
const [state, api] = useSequencer({
steps: [
['initial', 100],
['middle', 100],
['final', 0],
],
endMode: 'end',
complete: true,
})
Options
Options is an object passed to useSequencer
. It contains the following properties:
steps
steps: Array<[any, number]>
Pass an array of tuples that defines the steps of the sequence. The first value should be the name of the step, the second the duration in milliseconds.
useSequencer({
steps: [
['initial', 100],
['middle', 100],
['final', 0],
],
})
If you specify a duration of 0
for a step, it means that the following step will fire on the next animation frame. This guarantees that every state must be visited and rendered before transitioning to the next state.
This is useful for creating an animation 'set up' state where you may want to prepare some css before an animation begins. You can simply do this without needing to change anything else in your sequence:
const steps = [
['pre', 0],
['initial', 100],
['middle', 100],
['final', 0],
]
pre
becomes the default state when your component mounts, until the sequencer is started, which moves on to initial
on the next frame. By defining all the states explicitly in this fashion, it becomes easy to insert steps, change durations, swap steps and understand how your animation behaves.
endMode
endMode: 'end' | 'start' | 'loop'
The end mode determines the behavior of the sequencer once it reaches the end of the last step.
'end'
(default): The sequencer remains in the last step.'start'
: The sequencer resets to the first step and becomes idle.'loop'
: The sequencer resets to the first step and continues looping untilstop()
orpause()
is called.
autoplay
autoPlay: boolean
Set to true
to start playing the sequencer when your component mounts.
complete
complete: boolean
If set to true
, the sequencer is initialized in the 'completed' state, meaning it is in the final step and idle. It will remain in this state until either play()
or stop()
is called.
Sequencer State
The sequencer state is an object representing the current state of the sequencer. It includes these properties.
current
current: any
The current step of the sequencer, as specified by the step names provided in the config. While these examples use a string, you can actually use any type for your names.
index
index: number
The index of the current step.
isPlaying
isPlaying: boolean
true
if the sequencer is playing.
isComplete
isComplete: boolean
true
if the sequencer has finished sequencing through the steps and is idle. endMode
must be set to end
in order to reach this state.
isStopped
isStopped: boolean
true
if the sequencer is in its first step and not playing.
Sequencer Api
isBefore()
isBefore(name: string): boolean
true
if the sequencer has not yet reached the step with the provided name.
isAfter()
isAfter(name: string): boolean
true
if the sequencer has passed the step with the provided name.
play()
play(): void
Starts the sequencer, or continues playing if the sequencer was paused.
pause()
pause(): void
Pauses the sequencer. The sequencer tracks how far it is through the current step by the millisecond so that playback continues from the same moment.
stop()
stop(): void
Stops playback and resets the sequencer back to the first step.
complete()
complete(): void
Stops playback and puts the sequencer to the end of the final step.
Sequencer component
If you prefer you may also use a wrapper component <Sequencer>
to create a sequencer. Here you pass all the options
above as props, and you should pass a function as the child component with state
and api
as arguments:
import { Sequencer } from 'react-sequencer'
const MyComponent = (props) => {
return (
<Sequencer steps={mySteps}>
{(state, api) => <div>The current state is {state.current}</div>}
</Sequencer>
)
}
LICENSE
MIT