EventEmitter

EventEmitter

Implement EventEmitter on object or component.

Constructor

new EventEmitter()

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Methods

emit(eventName, paramopt) → {boolean}

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Fires an event to call listeners.
Name Type Default Description
eventName string | ... Event name
param? TargetParam<any> | ... {} Event parameter

emit<Name extends keyof Events, Param = Events[Name]>(eventName) → {boolean}

Name Type Description
eventName extends Param ? Name : never

emit<Name extends keyof Events, Param = Events[Name]>(eventName, param) → {boolean}

Name Type Description
eventName Name
param TargetParam<Param>
Example
import EventEmitter from "@scena/event-emitter";


const emitter = new EventEmitter();

emitter.on("a", e => {
});


emitter.emit("a", {
  a: 1,
});
Returns:
If false, stop the event.
Type
boolean

off(eventNameopt, listeneropt) → {this}

Source:
Remove listeners registered in the event target.
Name Type Description
eventName? string | object | ... Name of the event to be removed
listener? EventListener<Events[any], this> | ... listener function of the event to be removed

off<Name extends keyof Events, Param = Events[Name]>(eventName, listener) → {this}

Name Type Description
eventName? Name
listener? EventListener<Param, this>

off(events) → {this}

Name Type Description
events EventHash<Events, this>
Example
import EventEmitter from "@scena/event-emitter";
cosnt emitter = new EventEmitter();

// Remove all listeners.
emitter.off();

// Remove all listeners in "A" event.
emitter.off("a");


// Remove "listener" listener in "a" event.
emitter.off("a", listener);
Returns:
Type
this

on(eventName, listeneropt) → {this}

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Add a listener to the registered event.
Name Type Description
eventName string | object | ... Name of the event to be added
listener? EventListener<Events[any], this> | ... listener function of the event to be added

on<Name extends keyof Events, Param = Events[Name]>(eventName, listener) → {this}

Name Type Description
eventName Name
listener EventListener<Param, this>

on(events) → {this}

Name Type Description
events EventHash<Events, this>
Example
import EventEmitter from "@scena/event-emitter";
cosnt emitter = new EventEmitter();

// Add listener in "a" event
emitter.on("a", () => {
});
// Add listeners
emitter.on({
 a: () => {},
 b: () => {},
});
Returns:
Type
this

once<Name extends keyof Events & string, Param = Events[Name]>(eventName, listeneropt) → {Promise<OnEvent<Param, this>>}

Source:
Add a disposable listener and Use promise to the registered event.
Name Type Description
eventName Name Name of the event to be added
listener? EventListener<Param, this> disposable listener function of the event to be added
Example
import EventEmitter from "@scena/event-emitter";
cosnt emitter = new EventEmitter();

// Add a disposable listener in "a" event
emitter.once("a", () => {
});

// Use Promise
emitter.once("a").then(e => {
});
Returns:
Type
Promise<OnEvent<Param, this>>

trigger<Name extends keyof Events>(eventName, paramopt) → {boolean}

Source:
Fires an event to call listeners.
Name Type Default Description
eventName Name | ... Event name
param? TargetParam<any> | ... {} Event parameter

trigger<Name extends keyof Events, Param = Events[Name]>(eventName) → {boolean}

Name Type Description
eventName extends Param ? Name : never

trigger<Name extends keyof Events, Param = Events[Name]>(eventName, param) → {boolean}

Name Type Description
eventName Name
param TargetParam<Param>
Example
import EventEmitter from "@scena/event-emitter";


const emitter = new EventEmitter();

emitter.on("a", e => {
});


emitter.emit("a", {
  a: 1,
});
     
Returns:
If false, stop the event.
Type
boolean

trigger<Name extends keyof Events>(eventName, paramopt) → {boolean}

Source:
Fires an event to call listeners.
Name Type Default Description
eventName Name | ... Event name
param? TargetParam<any> | ... {} Event parameter

trigger<Name extends keyof Events, Param = Events[Name]>(eventName) → {boolean}

Name Type Description
eventName extends Param ? Name : never

trigger<Name extends keyof Events, Param = Events[Name]>(eventName, param) → {boolean}

Name Type Description
eventName Name
param TargetParam<Param>
Example
import EventEmitter from "@scena/event-emitter";


const emitter = new EventEmitter();

emitter.on("a", e => {
});

// emit
emitter.trigger("a", {
  a: 1,
});
Returns:
If false, stop the event.
Type
boolean

Type Definitions

EmitterParam<Target = any>

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Properties:
Name Type Description
type string
currentTarget Target
stop () => void
Type:
  • TSInterface

EventHash<Events, Target>

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Type:
  • Partial<[Key extends keyof Events]: EventListener<Events[Key], Target>>

EventInfo

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Properties:
Name Type Description
listener EventListener<any, any>
Type:
  • TSInterface

EventListener<Param, Target>

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Type:
  • (e: OnEvent<Param, Target>) => any

EventOptions

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Properties:
Name Type Description
once boolean
Type:
  • TSInterface

OnEvent<Param, Target = any>

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Type:

TargetParam<Param>

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Type: