Memory management best practices in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new buffer of 10 bytes in Node.js.

Node.js

const buffer = Buffer.[1](10);

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Amake

Bcreate

Cnew

Dalloc

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'new Buffer()' which is deprecated and unsafe.

Trying to use 'Buffer.create()' which does not exist.

The Buffer.alloc(size) method creates a new buffer of the specified size filled with zeros. This is the safe way to allocate memory in Node.js.

2fill in blank

medium

Complete the code to free up memory by clearing a large object reference.

Node.js

let largeObject = { data: 'some large data' };
// When done, set to [1] to help garbage collection

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Anull

B0

Cundefined

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the variable to 0 or false does not remove the object reference.

Setting to undefined is possible but null is clearer for intent.

Setting a variable to null removes the reference to the object, allowing Node.js garbage collector to reclaim memory.

3fill in blank

hard

Fix the error in the code to avoid memory leaks by removing event listeners properly.

Node.js

const EventEmitter = require('events');
const emitter = new EventEmitter();

function onData() {
  console.log('Data received');
}
emitter.on('data', onData);

// To prevent leaks, remove listener with emitter.[1]('data', onData);

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AremoveListener

BdeleteListener

Coff

DremoveEvent

Attempts:

3 left

💡 Hint

Common Mistakes

Using removeEvent which does not exist.

Using deleteListener which is not a method.

The off method is the modern way to remove event listeners in Node.js, preventing memory leaks.

4fill in blank

hard

Fill both blanks to create a WeakMap and add an object key with a value.

Node.js

const [1] = new [2]();
const objKey = {};
weakMap.set(objKey, 'value');

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AweakMap

BWeakMap

CMap

Dweakmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using Map instead of WeakMap which does not allow garbage collection of keys.

Using lowercase weakmap which is not a valid constructor.

A WeakMap allows keys to be garbage collected if there are no other references. Naming the variable weakMap is a common convention.

5fill in blank

hard

Fill all three blanks to create a memory-efficient cache using a WeakMap and add an entry.

Node.js

const [1] = new [2]();
const user = { id: 1 };
[3].set(user, { name: 'Alice' });

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Acache

BWeakMap

DMap

Attempts:

3 left

💡 Hint

Common Mistakes

Using Map instead of WeakMap which keeps strong references.

Using inconsistent variable names.

Using a WeakMap named cache helps store data linked to objects without preventing garbage collection.