Node.js · Junior · Question 41 of 75

What will this code print?

import { EventEmitter } from "node:events";
const bus = new EventEmitter();
bus.once("ping", () => console.log("pong"));
bus.emit("ping");
bus.emit("ping");

✓Correct answer: pong once
2Nothing
3pong twice

Explanation

once removes the listener after the first call. With on the listener would run every time.

Further reading

Node.js API: Events ↗

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