Constructor

The core event emitter class FastEvent provides publish/subscribe functionality, supporting:

• Event subscription (on/once)
• Event emission (emit/emitAsync)
• Wildcard matching
• Event scopes (scope)
• Retained events (retain)
• Asynchronous event handling

Constructor

constructor(options?: FastEventOptions<Meta, Context>)


 type FastEventOptions<Meta = Record<string, any>, Context = any> = {
    id?: string
    debug?: boolean
    // Event delimiter
    delimiter?: string
    // Execution context for listener functions
    context?: Context
    // Whether to ignore errors thrown by listener functions, defaults to true
    ignoreErrors?: boolean
    // Extra global metadata, passed to listeners when an event is emitted
    meta?: Meta
    // Callback when a new listener is created
    onAddListener?: (type: string[], listener: FastEventListener) => void
    // Callback when a listener is removed
    onRemoveListener?: (type: string[], listener: FastEventListener) => void
    // Callback when all listeners are cleared
    onClearListeners?: () => void
    // Callback when a listener function throws an error, used for diagnostics; can print the error
    onListenerError?: ((type: string, error: Error) => void)
    // Callback before executing a listener; returning false cancels execution
    onBeforeExecuteListener?: (message: FastEventMessage<any, Meta>, args: FastEventListenerArgs<Meta>) => boolean | void
    // Callback after executing a listener
    onAfterExecuteListener?: (message: FastEventMessage<any, Meta>, returns: any[], listeners: FastListenerNode[]) => void
    // Global executor
    executor?: FastListenerExecutorArgs
}

id

• Type: string
• Default: auto-generated

Optional, unique identifier.

debug

• Type: boolean
• Default: false

Optional, debug mode. When enabled, you can use Redux DevTools to debug events. See Debugging Tools for details.

delimiter

• Type: string
• Default: /

Optional, event delimiter used to separate multi-level events.

context

• Type: any
• Default: this

Optional, execution context for listener functions. Defaults to the FastEvent instance.

ignoreErrors

• Type: boolean
• Default: true

Optional, whether to ignore errors thrown by listener functions. Defaults to true, meaning errors are caught and an error object is returned instead of being thrown.

meta

• Type: Meta
• Default: undefined

Optional, global metadata passed to listener functions when an event is emitted.

onAddListener

• Type: (type: string[], listener: FastEventListener) => void
• Default: undefined

Optional, callback invoked when a new listener is created.

onRemoveListener

• Type: (type: string[], listener: FastEventListener) => void
• Default: undefined

Optional, callback invoked when a listener is removed.

onClearListeners

• Type: () => void
• Default: undefined

Optional, callback invoked when all listeners are cleared.

onListenerError

• Type: (type: string, error: Error) => void
• Default: undefined

Optional, callback invoked when a listener function throws an error. Used for diagnostics; can be used to print error information.

onBeforeExecuteListener

• Type: (message: FastEventMessage<any, Meta>, args: FastEventListenerArgs<Meta>) => boolean | void
• Default: undefined

Optional, callback invoked before executing a listener. Returning false cancels the execution.

onAfterExecuteListener

• Type: (message: FastEventMessage<any, Meta>, returns: any[], listeners: FastListenerNode[]) => void
• Default: undefined

Optional, callback invoked after executing a listener.

executor

• Type: FastListenerExecutorArgs
• Default: undefined

Optional, global executor used to customize how listener functions are executed.

Generic Parameters

class FastEvent<
    Events extends FastEvents = FastEvents,
    Meta extends Record<string, any> = Record<string, any>,
    Context = never,
    Types extends keyof Events = Exclude<keyof Events, number | symbol>
>

Events

Event type definition, extends the FastEvents interface.

Meta

Global event metadata type.

Context

Execution context type for listener functions.

Types

Key type of the event types; defaults to the key type of Events.