In-memory caching with node-cache in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the NodeCache library.

Express

const NodeCache = require('[1]');

Drag options to blanks, or click blank then click option'

Anode-cache

Bexpress

Ccache-node

Dmemory-cache

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'express' instead of 'node-cache'.

Mixing up package names like 'memory-cache'.

The correct package name to import is node-cache.

2fill in blank

medium

Complete the code to create a new cache instance.

Express

const cache = new NodeCache({ stdTTL: [1] });

Drag options to blanks, or click blank then click option'

A1000

B60

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting TTL to 0 disables expiration, which is not typical here.

Using a very large number like 1000 seconds without reason.

The stdTTL option sets the default time-to-live in seconds. 60 seconds is a common choice.

3fill in blank

hard

Fix the error in setting a cache value with key 'user' and value 'John'.

Express

cache.[1]('user', 'John');

Drag options to blanks, or click blank then click option'

Aget

Bput

Cadd

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' instead of 'set' causes no data to be saved.

Using 'add' or 'put' which are not methods in node-cache.

The method to store a value in the cache is set.

4fill in blank

hard

Fill both blanks to retrieve a cached value and handle a cache miss.

Express

const value = cache.[1]('key');
if (value === [2]) {
  console.log('Cache miss');
}

Drag options to blanks, or click blank then click option'

Aget

Bnull

Cundefined

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for null instead of undefined causes missed cache misses.

Using 'set' instead of 'get' to retrieve data.

Use get to retrieve the value. If the key is missing, get returns undefined.

5fill in blank

hard

Fill all three blanks to create a cache, set a value, and retrieve it.

Express

const cache = new NodeCache({ stdTTL: [1] });
cache.[2]('color', 'blue');
const color = cache.[3]('color');

Drag options to blanks, or click blank then click option'

A120

Bset

Cget

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'delete' instead of 'get' to retrieve data.

Setting TTL to 0 disables expiration unintentionally.

We create a cache with TTL 120 seconds, set the key 'color' to 'blue', then get it back.