Response time optimization in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple HTTP server that responds quickly.

Node.js

import http from 'http';

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end([1]);
});

server.listen(3000);

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Aconsole.log('Hello')

Bawait fetch('data')

C'Hello, world!'

Dres.write('Hello')

Attempts:

3 left

💡 Hint

Common Mistakes

Using asynchronous calls inside res.end()

Trying to log instead of sending response

The server should send a simple string response immediately using res.end() with a string. Using 'Hello, world!' sends a quick response.

2fill in blank

medium

Complete the code to cache the response data in memory for faster subsequent responses.

Node.js

let cache = null;

const server = http.createServer((req, res) => {
  if (cache) {
    res.end(cache);
  } else {
    const data = 'Cached response';
    cache = [1];
    res.end(data);
  }
});

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Anull

Bawait data

Cres.end(data)

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning res.end(data) to cache

Using await incorrectly

To cache the response, assign the data string to the cache variable so it can be reused later.

3fill in blank

hard

Fix the error in the asynchronous data fetching to improve response time by caching the result.

Node.js

let cache = null;

async function fetchData() {
  if (cache) return cache;
  cache = await [1];
  return cache;
}

const server = http.createServer(async (req, res) => {
  const data = await fetchData();
  res.end(data);
});

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Afetch('https://api.example.com/data').then(res => res.text())

Bfetch('https://api.example.com/data')

Cres.end('data')

D'https://api.example.com/data'

Attempts:

3 left

💡 Hint

Common Mistakes

Caching the fetch promise directly

Using string URL instead of fetch call

The fetch call must be followed by .then(res => res.text()) to get the response body as text before caching it.

4fill in blank

hard

Fill both blanks to implement compression middleware for faster response delivery.

Node.js

import express from 'express';
import [1] from 'compression';

const app = express();
app.use([2]());

app.get('/', (req, res) => {
  res.send('Hello with compression');
});

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Acompression

Bcors

Dhelmet

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong middleware like cors or helmet

Not calling the middleware function

To enable compression, import the compression package and use it as middleware with app.use(compression()).

5fill in blank

hard

Fill all three blanks to implement a simple cache with expiration for API responses.

Node.js

const cache = new Map();
const CACHE_TIME = 60000; // 1 minute

async function getData(key) {
  const cached = cache.get(key);
  if (cached && (Date.now() - cached.timestamp) < [1]) {
    return cached.value;
  }
  const value = await fetch(key).then(res => res.text());
  cache.set(key, { value: [2], timestamp: [3] });
  return value;
}

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ACACHE_TIME

Bvalue

CDate.now()

Dkey

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variables for cache values

Not setting timestamp correctly

The cache expiration uses CACHE_TIME. The cached value is value, and the timestamp is set to Date.now().