method EventEmitter.once
Usage in Deno
```typescript import { type EventEmitter } from "node:node__events.d.ts"; ```
EventEmitter.once<K>(): this
Adds a **one-time** `listener` function for the event named `eventName`. The
next time `eventName` is triggered, this listener is removed and then invoked.
```js
server.once('connection', (stream) => {
console.log('Ah, we have our first user!');
});
```
Returns a reference to the `EventEmitter`, so that calls can be chained.
By default, event listeners are invoked in the order they are added. The `emitter.prependOnceListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.
```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
// b
// a
```
this