data-state

Fast state based on top of typed arrays.

A simple typed array state container that is fast and scalable.

var state = createState({
  type: Float32Array
}, function dispatch (index, value, oldValue) {
  // Handle value changes on the data
})
 
for (var i = 0; i < 100) {
  state.stage(i, Math.random())
}
 
state.update()

I might use it in managing coordinates in canvas, and videos/audio processing. Or maybe any time I want a fast/simple Set:

var state = createState()
 
state.set(0, 123)
state.get(0) === 123

Installation

$ npm install --save data-state

Usage

createState([options], dispatch)

Create state and container for data. Returns state functions.

Parameters

• options (Object): Options for your state and data.
  • type (TypedArray): A TypedArray interface for the data backing your state. Defaults to Float32Array.
  • data (ArrayBuffer): A buffer to initialize the typed array with. (Note: overrides length if set)
  • length (Number): Alternative to data, initialize empty typed array at specified length. Defaults to 10000.
  • lowSecurity (Boolean): Makes the dump() return state internals. Defaults to false.
• dispatch (Function): Dispatch function triggered every time you update.

Dispatch

Updates are called on your function like dispatch(index, value, oldValue). This is called by both state.set() and state.update().

Example

var state = createState({
  type: Uint16Array,
  length: 500 // Maximum amount of data.
}, function (i, value, oldValue) {
  // Dispatch on update
})

state.get(index)

Return value at the given index number.

Example

var foo = state({ data: someExistingData })
 
var value = foo.get(10)

state.set(index, value)

Set value at the given index number. This calls a dispatch after (opposed to state.stage()).

Example

var state = createState({ type: Float32Array })
 
state.set(0, 100)
state.get(0) === 100
 
state.set(1, 0.005)

state.stage(index, value)

Stages the setting of value at the given index number. Values are dispatched when state.update() is called.

Example

var state = createState()
 
state.stage(1, 123)
stage.get(1) !== 123
// Update it, set staged values
stage.update()
stage.get(1) === 123

state.update()

Sets staged values, dispatching them in ascending order of their index numbers.

Example

var state = createState({
  type: Float32Array
}, function dispatch (index, value, oldValue) {
  // Handle value changes on the data
})
 
for (var i = 0; i < 100) {
  state.stage(i, Math.random())
}
 
state.update()

state.length()

Get length of state's array.

Example

var state = createState({ length: 10 })
 
// Get length
state.length() === 10

state.dump()

This only returns null by default. It can be a risk if you do not want access to any of the data below (i.e. passing to plugins). It can be useful for debugging and unit testing though.

Returns an object containing data, staging, dispatch, and options.

Example

var state = createState({ lowSecurity: true })
 
var internals = state.dump()
internals.staging[0] = 123
internals.data.buffer
internals.dispatch(10, 0.101, 0.001)
// ...

License

MIT © Jamen Marz