Asynchronous Programming – Promises

Exercise 1 - File System with Promises (Node.js)

Using the Node.js Promises API for file access, complete the tasks described below.

You must implement two separate functions, each with a clear and well-defined responsibility.

Function 1 - readAndFilter()

Implement a function called readAndFilter() that does the following:

1. Reads the liga.json file using fs.promises.readFile.
2. Parses the file contents from JSON into a JavaScript object or array using the JSON.parse function.
3. Filters the teams and returns only those whose number of goals scored (goals) is greater than 10.
4. Returns the filtered array.

Function 2 - saveResult(filteredTeams)

Implement a function called saveResult() that:

1. Receives the filtered array returned by readAndFilter().
2. Converts this array into formatted JSON using JSON.stringify(filteredTeams).
3. Writes the result to a new file called liga10goals.json using fs.promises.writeFile.

Final Goal

Create a small main() function (or similar control code) that:

1. Calls readAndFilter() to obtain the filtered teams.
2. Passes the result to saveResult().

When executed, the program should produce the file:

liga10goals.json

containing only the teams that scored more than 10 goals.

Example Result (inside liga10goals.json)

[
  {
    "name": "Benfica",
    "goals": 12,
    "points": 30
  },
  {
    "name": "Porto",
    "goals": 15,
    "points": 28
  },
  {
    "name": "Sporting",
    "goals": 11,
    "points": 27
  }
]

Exercise 2 - Fetch API (Node.js)

Using the Fetch API, write a program that retrieves information about animated movies from a web API and saves the titles of all movies to a local JSON file.

You must implement two separate functions, each with a clear and well-defined responsibility.

Function 1 - fetchMovies()

Implement a function called fetchMovies() that does the following:

Makes an HTTP GET request to:

https://api.sampleapis.com/movies/animation

1. Uses the Fetch API to retrieve the data.
2. Parses the response as JSON using response.json().
3. Extracts only the titles of the movies from the returned objects.
4. Returns an array of movie titles.

Function 2 - saveTitles(titles)

Implement a function called saveTitles() that:

1. Receives the array of movie titles returned by fetchMovies().
2. Converts the array into formatted JSON using:

JSON.stringify(titles, null, 2)

Saves this JSON to a file called:

animationTitles.json

using fs.promises.writeFile.

Final Goal

Write a small main() function (or similar) that:

1. Calls fetchMovies() to obtain the titles.
2. Passes the result to saveTitles().

When executed, the program should create the file:

animationTitles.json

containing all the movie titles retrieved from the API.

Example Result (inside animationTitles.json)

[
  "Spirited Away",
  "Toy Story",
  "How to Train Your Dragon",
  "Zootopia"
]

The actual titles will depend on the API response.