79 lines
2.5 KiB
TypeScript
79 lines
2.5 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 = (event?: any) => 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 {
|
||
|
|
on(type: EventType, handler: Handler): void;
|
||
|
|
on(type: '*', handler: WildcardHandler): void;
|
||
|
|
|
||
|
|
off(type: EventType, handler: Handler): void;
|
||
|
|
off(type: '*', handler: WildcardHandler): void;
|
||
|
|
|
||
|
|
emit<T = any>(type: EventType, event?: T): void;
|
||
|
|
emit(type: '*', event?: any): void;
|
||
|
|
}
|
||
|
|
|
||
|
|
/** Mitt: Tiny (~200b) functional event emitter / pubsub.
|
||
|
|
* @name mitt
|
||
|
|
* @returns {Mitt}
|
||
|
|
*/
|
||
|
|
export default function mitt(all?: EventHandlerMap): Emitter {
|
||
|
|
all = all || new Map();
|
||
|
|
|
||
|
|
return {
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 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(type: EventType, handler: Handler) {
|
||
|
|
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(type: EventType, handler: Handler) {
|
||
|
|
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(type: EventType, evt: any) {
|
||
|
|
((all.get(type) || []) as EventHandlerList).slice().map((handler) => { handler(evt); });
|
||
|
|
((all.get('*') || []) as WildCardEventHandlerList).slice().map((handler) => { handler(type, evt); });
|
||
|
|
}
|
||
|
|
};
|
||
|
|
}
|