/**
|
* copy to https://github.com/developit/mitt
|
* Expand clear method
|
*/
|
|
export type EventType = string | symbol;
|
|
// An event handler can take an optional event argument
|
// and should not return a value
|
export type Handler<T = any> = (event?: T) => void;
|
export type WildcardHandler = (type: EventType, event?: any) => void;
|
|
// An array of all currently registered event handlers for a type
|
export type EventHandlerList = Array<Handler>;
|
export type WildCardEventHandlerList = Array<WildcardHandler>;
|
|
// A map of event types and their corresponding event handlers.
|
export type EventHandlerMap = Map<EventType, EventHandlerList | WildCardEventHandlerList>;
|
|
export interface Emitter {
|
all: EventHandlerMap;
|
|
on<T = any>(type: EventType, handler: Handler<T>): void;
|
on(type: '*', handler: WildcardHandler): void;
|
|
off<T = any>(type: EventType, handler: Handler<T>): void;
|
off(type: '*', handler: WildcardHandler): void;
|
|
emit<T = any>(type: EventType, event?: T): void;
|
emit(type: '*', event?: any): void;
|
clear(): void;
|
}
|
|
/**
|
* Mitt: Tiny (~200b) functional event emitter / pubsub.
|
* @name mitt
|
* @returns {Mitt}
|
*/
|
export default function mitt(all?: EventHandlerMap): Emitter {
|
all = all || new Map();
|
|
return {
|
/**
|
* A Map of event names to registered handler functions.
|
*/
|
all,
|
|
/**
|
* 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
|
*/
|
on<T = any>(type: EventType, handler: Handler<T>) {
|
const handlers = all?.get(type);
|
const added = handlers && handlers.push(handler);
|
if (!added) {
|
all?.set(type, [handler]);
|
}
|
},
|
|
/**
|
* Remove an event handler for the given type.
|
* @param {string|symbol} type Type of event to unregister `handler` from, or `"*"`
|
* @param {Function} handler Handler function to remove
|
* @memberOf mitt
|
*/
|
off<T = any>(type: EventType, handler: Handler<T>) {
|
const handlers = all?.get(type);
|
if (handlers) {
|
handlers.splice(handlers.indexOf(handler) >>> 0, 1);
|
}
|
},
|
|
/**
|
* 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<T = any>(type: EventType, evt: T) {
|
((all?.get(type) || []) as EventHandlerList).slice().map((handler) => {
|
handler(evt);
|
});
|
((all?.get('*') || []) as WildCardEventHandlerList).slice().map((handler) => {
|
handler(type, evt);
|
});
|
},
|
|
/**
|
* Clear all
|
*/
|
clear() {
|
this.all.clear();
|
},
|
};
|
}
|
