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cache map.get() for size wins #100

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merged 2 commits into from
May 27, 2020
Merged

cache map.get() for size wins #100

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a400ffd
cache map.get() for size wins
developit May 26, 2020
876168d
Further reduce size of on()
developit May 26, 2020
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16 changes: 9 additions & 7 deletions src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,21 +27,22 @@ export interface Emitter {
* @name mitt
* @returns {Mitt}
*/
export default function mitt(all: EventHandlerMap): Emitter {
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) || []);
handlers.push(handler);
all.set(type, handlers);
const handlers = all.get(type);
const added = handlers && handlers.push(handler);
if (!added) {
all.set(type, [handler]);
}
},

/**
Expand All @@ -52,8 +53,9 @@ export default function mitt(all: EventHandlerMap): Emitter {
* @memberOf mitt
*/
off(type: EventType, handler: Handler) {
if (all.has(type)) {
all.get(type).splice(all.get(type).indexOf(handler) >>> 0, 1);
const handlers = all.get(type);
if (handlers) {
handlers.splice(handlers.indexOf(handler) >>> 0, 1);
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Wouldn't it be better to use Set for the handlers instead?

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For speed yes, but Set rejects duplicates. EventEmitter, the API contract mitt adheres to, allows duplicate handlers.

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Does that mean I can register the same functions twice? That is really interesting.

}
},

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