bndr-js - v0.18.0 / Emitter

Class: Emitter<T>

A foundational value of the library, an instance representing a single event emitter. This could be user input from a mouse, keyboard, MIDI controller, gamepad etc., or the result of filtering or composing these inputs. Various operations can be attached by method chaining.

Type parameters

Name	Type
`T`	`any`

Hierarchy

Emitter
↳ GamepadEmitter
↳ KeyboardEmitter
↳ MidiEmitter
↳ PointerEmitter

Constructors

constructor

• new Emitter<T>(options?)

Type parameters

Name	Type
`T`	`any`

Parameters

Name	Type
`options`	`EmitterOptions`<`T`>

Defined in

src/Emitter.ts:37open in new window

Common Filters

change

▸ change(equalFn?): Emitter<T>

Emits only when the value is changed

Parameters

Name	Type	Default value	Description
`equalFn`	(`a`: `T`, `b`: `T`) => `boolean`	`isEqual`	A comparator function. The event will be emitted when the function returns falsy value.

Returns

Defined in

src/Emitter.ts:305open in new window

constant

▸ constant<U>(value): Emitter<U>

Creates an emitter that emits a constant value every time the current emitter is emitted.

Type parameters

Name
`U`

Parameters

Name	Type
`value`	`U`

Returns

See

https://lodash.com/docs/4.17.15#throttleopen in new window

Defined in

src/Emitter.ts:393open in new window

debounce

▸ debounce(wait, options): Emitter<unknown>

Creates debounced version of the current emitter.

Parameters

Name	Type	Description
`wait`	`number`	Milliseconds to wait.
`options`	`DebounceSettings`

Returns

Emitter<unknown>

A new emitter

Defined in

src/Emitter.ts:435open in new window

delay

▸ delay(wait): Emitter<unknown>

Creates delayed version of the current emitter.

Parameters

Name	Type	Description
`wait`	`number`	Milliseconds to wait.

Returns

Emitter<unknown>

A new emitter

Defined in

src/Emitter.ts:460open in new window

delta

▸ delta<U>(fn): Emitter<U>

Creates an emitter that emits the ‘difference’ between the current value and the previous value.

Type parameters

Name
`U`

Parameters

Name	Type	Description
`fn`	(`prev`: `T`, `curt`: `T`) => `U`	A function to calculate the difference

Returns

A new emitter

Defined in

src/Emitter.ts:679open in new window

down

▸ down(): Emitter<true>

Creates an emitter that emits at the moment the current value changes from falsy to truthy.

Returns

Emitter<true>

Defined in

src/Emitter.ts:268open in new window

filter

▸ filter(fn): Emitter<T>

Filters events with the given predicate function

Parameters

Name	Type	Description
`fn`	(`value`: `T`) => `any`	Return truthy value to pass events

Returns

A new emitter

Defined in

src/Emitter.ts:237open in new window

filterMap

▸ filterMap<U>(fn, initialValue?): Emitter<U>

Maps the current value to another type of value, and emits the mapped value only when the mapped value is not undefined.

Type parameters

Name
`U`

Parameters

Name	Type	Description
`fn`	(`value`: `T`) => `U`	A function to map the current value. Return `undefined` to skip emitting.
`initialValue?`	`U`	-

Returns

Defined in

src/Emitter.ts:252open in new window

fold

▸ fold<U>(fn, initialState): Emitter<U>

Initializes with an initialState value. On each emitted event, calculates a new state based on the previous state and the current value, and emits this new state.

Type parameters

Name
`U`

Parameters

Name	Type	Description
`fn`	(`prev`: `U`, `value`: `T`) => `U`	A function to calculate a new state
`initialState`	`U`	An initial state value

Returns

A new emitter

Defined in

src/Emitter.ts:633open in new window

interval

▸ interval(ms?, immediate?): Emitter<any>

Creates an emitter that keeps to emit the last value of the current emitter at the specified interval.

Parameters

Name	Type	Default value	Description
`ms`	`number`	`0`	The interval in milliseconds. Set `0` to use `requestAnimationFrame`.
`immediate`	`boolean`	`false`	If set to `false`, the new emitter waits to emit until the current emitter emits any value.

Returns

Emitter<any>

A new emitter.

Defined in

src/Emitter.ts:702open in new window

lerp

▸ lerp(lerp, rate, threshold?): Emitter<T>

Smoothen the change rate of the input value.

Parameters

Name	Type	Default value	Description
`lerp`	`Lerp`<`T`>	`undefined`	A function to interpolate the current value and the target value.
`rate`	`number`	`undefined`	The ratio of linear interpolation from the current value to the target value with each update.
`threshold`	`number`	`1e-4`	The threshold to determine whether the current value is close enough to the target value. If the difference between the current value and the target value is less than this value, the target value will be used as the current value and the interpolation will be stopped.

Returns

A new emitter

Defined in

src/Emitter.ts:506open in new window

longPress

▸ longPress(wait): Object

Parameters

Name	Type
`wait`	`number`

Returns

Object

Name	Type
`pressed`	`Emitter`<`unknown`>

Defined in

src/Emitter.ts:476open in new window

map

▸ map<U>(fn, initialValue?): Emitter<U>

Transforms the payload of event with the given function.

Type parameters

Name
`U`

Parameters

Name	Type	Description
`fn`	(`value`: `T`) => `U`	A function to transform the payload
`initialValue?`	`U`	-

Returns

A new emitter

Defined in

src/Emitter.ts:224open in new window

not

▸ not(): Emitter<boolean>

Creates an emitter whose payload is negated.

Returns

Emitter<boolean>

Defined in

src/Emitter.ts:294open in new window

resetBy

▸ resetBy(emitter, emitOnReset?): Emitter<T>

Reset the state of current emitter emitter when the given event is fired.

Parameters

Name	Type	Default value	Description
`emitter`	`Emitter`<`any`>	`undefined`	The emitter that triggers the current emitter to be reset.
`emitOnReset`	`boolean`	`true`	If set to `true`, the current emitter will be triggered when it is reset.

Returns

The current emitter emitter

Defined in

src/Emitter.ts:610open in new window

stash

▸ stash(...triggers): Emitter<any>

Creates an emitter that emits the current value when one of the given events is fired.

Parameters

Name	Type	Description
`...triggers`	`Emitter`<`any`>[]	Emitters to trigger the current emitter to emit.

Returns

Emitter<any>

A new emitter

Defined in

src/Emitter.ts:659open in new window

throttle

▸ throttle(wait, options?): Emitter<T>

Creates throttled version of the current emitter.

Parameters

Name	Type	Description
`wait`	`number`	Milliseconds to wait.
`options?`	`ThrottleSettings`

Returns

See

https://lodash.com/docs/4.17.15#debouncedopen in new window

Defined in

src/Emitter.ts:410open in new window

trail

▸ trail(count?, emitAtCount?): Emitter<T[]>

Emits an array caching a specified number of values that were emitted in the past.

Parameters

Name	Type	Default value	Description
`count`	`number`	`2`	The number of cache frames. Set `0` to store caches infinitely.
`emitAtCount`	`boolean`	`true`	When set to `true`, events will not be emitted until the count of cache reaches to `count`.

Returns

Emitter<T[]>

Defined in

src/Emitter.ts:739open in new window

up

▸ up(): Emitter<true>

Creates an emitter that emits at the moment the current value changes from falsy to truthy.

Returns

Emitter<true>

Defined in

src/Emitter.ts:281open in new window

while

▸ while(emitter, resetOnDown?): Emitter<T>

Emits while the given event is truthy. The event will be also emitted when the given emitter is changed from falsy to truthy when the resetOnDown flag is set to true.

Parameters

Name	Type	Default value	Description
`emitter`	`Emitter`<`boolean`>	`undefined`	An emitter to filter the events
`resetOnDown`	`boolean`	`true`	If set to `true`, the returned emitter will be reset when the given emitter is down.

Returns

Defined in

src/Emitter.ts:326open in new window

Methods

createDerived

▸ createDerived<U>(options): Emitter<U>

Type parameters

Name
`U`

Parameters

Name	Type
`options`	`EmitterOptions`<`U`> & { `propagate`: (`e`: `T`, `emit`: (`v`: `U`) => `void`) => `void` }

Returns

Defined in

src/Emitter.ts:80open in new window

registerDerived

▸ registerDerived(emitter, listener): void

Parameters

Name	Type
`emitter`	`Emitter`<`any`>
`listener`	`Listener`<`T`>

Returns

void

Defined in

src/Emitter.ts:72open in new window

tween

▸ tween(lerp, durationMs): Emitter<T>

Parameters

Name	Type
`lerp`	`Lerp`<`T`>
`durationMs`	`number`

Returns

Defined in

src/Emitter.ts:560open in new window

Properties

_disposed

• Protected _disposed: boolean = false

Defined in

src/Emitter.ts:61open in new window

derivedEmitters

• Protected Readonly derivedEmitters: Map<Emitter<any>, Listener<T>>

Stores all deviced events and their listeners. They will not be unregistered by removeAllListeners.

Defined in

src/Emitter.ts:59open in new window

icon

• Optional icon: IconSequence

Defined in

src/Emitter.ts:49open in new window

stateful

• get stateful(): boolean

Returns true if the emitter has a state and can be reset.

Returns

boolean

Defined in

src/Emitter.ts:137open in new window

value

• get value(): T

The latest value emitted from the emitter. If the emitter has never fired before, it just returns undefined.

Returns

T

Defined in

src/Emitter.ts:162open in new window

Accessors

disposed

• get disposed(): boolean

Returns

boolean

Defined in

src/Emitter.ts:63open in new window

Commom Filters

split

▸ split(emitter, count, resetOnSwitch?): Emitter<T>[]

Splits the current emitter into multiple emitters. Each emitter emits only when the given emitter is changed to the corresponding index.

Parameters

Name	Type	Default value	Description
`emitter`	`Emitter`<`any`>	`undefined`	An emitter to filter the current event
`count`	`number`	`undefined`	The number of emitters to be created.
`resetOnSwitch`	`boolean`	`true`	If set to `true`, the corresponding emitter will be reset when the index of current emitter is switched.

Returns

Emitter<T>[]

Defined in

src/Emitter.ts:355open in new window

Event Handlers

dispose

▸ dispose(): void

Disposes the emitter immediately and prevent to emit any value in the future

Returns

void

Defined in

src/Emitter.ts:119open in new window

emit

▸ emit(value): void

Manually emits the event.

Parameters

Name	Type
`value`	`T`

Returns

void

Defined in

src/Emitter.ts:190open in new window

log

▸ log(message?): Emitter<T>

Parameters

Name	Type	Default value
`message`	`string`	`'Bndr'`

Returns

Defined in

src/Emitter.ts:757open in new window

off

▸ off(listener): void

Removes the listener function from the event.

Parameters

Name	Type
`listener`	`Listener`<`T`>

Returns

void

Defined in

src/Emitter.ts:181open in new window

on

▸ on(listener): Emitter<T>

Adds the listener function for the event.

Parameters

Name	Type	Description
`listener`	`Listener`<`T`>	The callback function

Returns

Defined in

src/Emitter.ts:171open in new window

once

▸ once(listener): void

Adds a one-time listener function for the event

Parameters

Name	Type
`listener`	`Listener`<`T`>

Returns

void

Defined in

src/Emitter.ts:202open in new window

removeAllListeners

▸ removeAllListeners(): void

Removes all listeners.

Returns

void

Defined in

src/Emitter.ts:214open in new window

reset

▸ reset(): void

Resets the state of the emitter.

Returns

void

Defined in

src/Emitter.ts:145open in new window