README.md

Exercise 03 - Webserver

This exercise aims to be a realistic use-case of TypeScript. We will build a simple webserver that runs and caches the ping tests under /ping from the last exercise. As a bonus task, the /products API mirrors a remote API and returns the filtered data.

The API already exists, only the implementation is missing. You can find the Postman and Bruno Collections in the exercise root.

Tasks

• fix the processing of the options in HttpClient.fetch()
• implement the missing business logic of the PingService
• implement the APIs in the ping router by using the PingService
• Bonus: implement the generic fetchJson() method that automatically JSON parses the HTTP response and casts it to the given generic type
• Bonus: export the interface ProductsPage so that it matches the response from https://dummyjson.com/products
• Bonus: implement the /products API by fetching on https://dummyjson.com/products and returning all products that cost more than 1000

Hints

Measuring time:

const now = Date.now();
await someAsyncMethod();
const duration = Date.now() - now; // in ms

Map, Filter, Reduce:

const numbers = [1, 2, 3, 4, 5];

// Using map to double each number
const doubledNumbers = numbers.map(num => num * 2);
console.log("Doubled numbers:", doubledNumbers);

// Using filter to find even numbers
const evenNumbers = numbers.filter(num => num % 2 === 0);
console.log("Even numbers:", evenNumbers);

// Using reduce to calculate the sum of all numbers
const sum = numbers.reduce((sum, num) => sum + num, 0);
console.log("Sum of numbers:", sum);