event

Strictly typed event emitter with asynciterator support.

Events should be defined as a literal object type where the key is the event name, and the value is a tuple with any amount of elements of any type.

The constructor takes an optional argument which defines the maximum amount of listeners per event, which defaults to 10. If this limit is surpassed, an error is thrown.

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⚠️ Events must be a type, and can't be an interface due to their design differences.

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type Events = {
  foo: [string];
  bar: [number, boolean];
};

class MyClass extends EventEmitter<Events> {}
const MyClassInstance = new MyClass();

function listener(num, bool) {}

// add a listener to the bar event
MyClassInstance.on("bar", listener);

// remove a listener from the bar event
MyClassInstance.off("bar", listener);

// remove all listeners from the bar event
MyClassInstance.off("bar");

// remove all listeners from the event emitter
MyClassInstance.off();

// add a one-time listener to the bar event
MyClassInstance.once("bar", listener);

// on, once, and off are chainable
MyClassInstance.on("bar", listener).off("bar", listener);

// emit the bar event with the wanted data
MyClassInstance.emit("bar", 42, true);

// listen to all events with an async iterator
for await (const event of MyClassInstance) {
  if (event.name === "bar") {
    // event.value is of type [number, boolean]
  }
}

// listen to a specific event with an async iterator
for await (const [num, bool] of MyClassInstance.on("bar")) {
}

// removes all listeners and closes async iterators
MyClassInstance.close("bar");

Maintainers

• crowlKats (@crowlKats)

Other

Contribution

Pull request, issues and feedback are very welcome. Code style is formatted with deno fmt and commit messages are done following Conventional Commits spec.

Licence

Copyright 2020-present, the denosaurs team. All rights reserved. MIT license.