BeginnerCoder
DonateLesson 13 — Event emitter
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Node is event-driven: things happen ("a request arrived", "a file finished") and code reacts. An event emitter keeps a list of listener functions per event name. on(name, fn) adds a listener; emit(name, data) calls all of them.
b.on("hello", (d) => console.log("got", d));
b.emit("hello", "world"); // got world
Note: this playground runs JavaScript in your browser, not in real Node, so Node-only tools (like fs or http) are not available. The exercise is a small plain-JS simulation of the Node idea. Real Node has this built in as EventEmitter.
Why it matters: servers, streams and sockets in Node are all event emitters.
Finish emit() so it calls every listener for the event. Both listeners should log.
Run your code — when the output matches the task, you will see a green check. Then mark the lesson complete.
Test your knowledgeA quick 3-question quiz on this lesson — instant feedback.