109 lines
3.4 KiB
TypeScript
109 lines
3.4 KiB
TypeScript
export type EventType = string | symbol;
|
|
|
|
// An event handler can take an optional event argument
|
|
// and should not return a value
|
|
export type Handler<T = unknown> = (event: T) => void;
|
|
export type WildcardHandler<T = Record<string, unknown>> = (
|
|
type: keyof T,
|
|
event: T[keyof T]
|
|
) => void;
|
|
|
|
// An array of all currently registered event handlers for a type
|
|
export type EventHandlerList<T = unknown> = Array<Handler<T>>;
|
|
export type WildCardEventHandlerList<T = Record<string, unknown>> = Array<WildcardHandler<T>>;
|
|
|
|
// A map of event types and their corresponding event handlers.
|
|
export type EventHandlerMap<Events extends Record<EventType, unknown>> = Map<
|
|
keyof Events | '*',
|
|
EventHandlerList<Events[keyof Events]> | WildCardEventHandlerList<Events>
|
|
>;
|
|
|
|
type GenericEventHandler<Events extends Record<EventType, unknown>> =
|
|
| Handler<Events[keyof Events]>
|
|
| WildcardHandler<Events>;
|
|
|
|
export class EventEmitter<Events extends Record<EventType, unknown>> {
|
|
|
|
/**
|
|
* A Map of event names to registered handler functions.
|
|
*/
|
|
public all: EventHandlerMap<Events>;
|
|
|
|
public constructor() {
|
|
this.all = new Map();
|
|
}
|
|
|
|
on<Key extends keyof Events>(type: Key, handler: Handler<Events[Key]>): void;
|
|
on(type: '*', handler: WildcardHandler<Events>): void;
|
|
|
|
/**
|
|
* Register an event handler for the given type.
|
|
* @param {string|symbol} type Type of event to listen for, or `'*'` for all events
|
|
* @param {Function} handler Function to call in response to given event
|
|
* @memberOf mitt
|
|
*/
|
|
public on<Key extends keyof Events>(type: Key, handler: GenericEventHandler<Events>) {
|
|
const handlers: Array<GenericEventHandler<Events>> | undefined = this.all!.get(type);
|
|
if (handlers) {
|
|
handlers.push(handler);
|
|
}
|
|
else {
|
|
this.all!.set(type, [handler] as EventHandlerList<Events[keyof Events]>);
|
|
}
|
|
}
|
|
|
|
off<Key extends keyof Events>(type: Key, handler?: Handler<Events[Key]>): void;
|
|
off(type: '*', handler: WildcardHandler<Events>): void;
|
|
|
|
/**
|
|
* Remove an event handler for the given type.
|
|
* If `handler` is omitted, all handlers of the given type are removed.
|
|
* @param {string|symbol} type Type of event to unregister `handler` from, or `'*'`
|
|
* @param {Function} [handler] Handler function to remove
|
|
* @memberOf mitt
|
|
*/
|
|
public off<Key extends keyof Events>(type: Key, handler?: GenericEventHandler<Events>) {
|
|
const handlers: Array<GenericEventHandler<Events>> | undefined = this.all!.get(type);
|
|
if (handlers) {
|
|
if (handler) {
|
|
handlers.splice(handlers.indexOf(handler) >>> 0, 1);
|
|
}
|
|
else {
|
|
this.all!.set(type, []);
|
|
}
|
|
}
|
|
}
|
|
|
|
emit<Key extends keyof Events>(type: Key, event: Events[Key]): void;
|
|
emit<Key extends keyof Events>(type: undefined extends Events[Key] ? Key : never): void;
|
|
|
|
/**
|
|
* Invoke all handlers for the given type.
|
|
* If present, `'*'` handlers are invoked after type-matched handlers.
|
|
*
|
|
* Note: Manually firing '*' handlers is not supported.
|
|
*
|
|
* @param {string|symbol} type The event type to invoke
|
|
* @param {Any} [evt] Any value (object is recommended and powerful), passed to each handler
|
|
* @memberOf mitt
|
|
*/
|
|
emit<Key extends keyof Events>(type: Key, evt?: Events[Key]) {
|
|
let handlers = this.all!.get(type);
|
|
if (handlers) {
|
|
(handlers as EventHandlerList<Events[keyof Events]>)
|
|
.slice()
|
|
.map((handler) => {
|
|
handler(evt!);
|
|
});
|
|
}
|
|
|
|
handlers = this.all!.get('*');
|
|
if (handlers) {
|
|
(handlers as WildCardEventHandlerList<Events>)
|
|
.slice()
|
|
.map((handler) => {
|
|
handler(type, evt!);
|
|
});
|
|
}
|
|
}
|
|
} |