A simple, lightweight, and fast event emitter.
import { LiteEmit } from "lite-emit";
interface Events {
foo: [string];
bar: ["bar", number, symbol];
baz: [42];
}
const emitter = new LiteEmit<Events>();
function fooListener1(str: string) {
console.log(str);
}
function fooListener2(str: string) {
console.log(str);
}
function fooListener3(str: string) {
console.log(str);
}
// Add listeners
emitter.on("foo", fooListener1);
emitter.on("foo", fooListener2);
emitter.on("foo", fooListener3);
emitter.emit("foo", "hello");
emitter.on("baz", (num) => {
console.log(num);
});
emitter.emit("baz", "42");
// 42
// You can retrieve an `off` function when adding a listener
const offQuxListener2 = emitter.on("qux", (str) => {
console.log(str);
});
emitter.emit("qux", "hello");
// Output:
// hello
offQuxListener2();
emitter.emit("qux", "hello");
// Output:
// <NONE>
// Remove a specified listener for a specified event
emitter.off("foo", fooListener1);
emitter.emit("foo", "hello");
// Output:
// hello
// hello
// Add wildcard listeners
// Always called on every emit, no matter if the event has listeners or not
emitter.on("*", (event, ...args) => {
console.log(`Wildcard listener: event=${event}, args=${args}`);
});
// Remove all listeners for a specified event
emitter.off("foo");
// Output:
// <NONE>
emitter.emit("baz", 42);
// Output:
// 42
// Remove all wildcard listeners
emitter.off("*");
// Remove all listeners for all events
emitter.off();