Salesforce JS-Dev-101 Exam - Topic 5 Question 5 Discussion

Comprehensive and Detailed Explanation From Exact Extract JavaScript Knowledge:

The question specifies:

The library ''uses events and callbacks to start the server''.

We want to ''set up an event and start the web server''.

Option C:

server((port) => { console.log('Listening on', port); });

This:

Calls server(...), which (by design in such libraries) typically starts the web server.

Passes a callback function that receives port when the server is ready.

Inside the callback, it logs 'Listening on '.

This matches the ''events and callbacks'' description: the callback is invoked when the server has started listening.

Why others are incorrect:

A . server.on('connect', ...)

Assumes server is an event emitter instance with a 'connect' event, which is not given. Also, this line alone would not start the server.

B . server.start();

Assumes a start method exists; the question says the library ''uses events and callbacks to start,'' implying invocation with a callback, not a plain start() call.

D . server();

Might start the server, but does not ''set up an event'' or callback to know when or where it is listening.

Therefore, C aligns with the described usage.

Concepts: callback-based APIs, starting servers with callbacks, event/callback style vs simple method calls.