content.html

/**
 * Groups music track titles by release year and sorts them alphabetically.
 *
 * @param {Object[]} tracks - An array of music track objects.
 * @returns {Object} - An object where the keys are years and values are sorted arrays of track titles.
 * @throws {Error} - If the input is not an array or contains invalid track objects.
 */
function getMusicTitlesByYear(tracks) {
    if (!Array.isArray(tracks)) {
      throw new Error("Invalid input: Expected an array of music track objects.");
    }

    // Check if there is no data (empty array)
  if (tracks.length === 0) {
    throw new Error("No data: The tracks array is empty.");
  }
  
    const result = {};
  
    for (const track of tracks) {
      if (
        typeof track !== "object" ||
        !track.title ||
        typeof track.title !== "string" ||
        !track.artist ||
        typeof track.artist !== "string" ||
        !track.year ||
        typeof track.year !== "number" ||
        isNaN(track.year)
      ) {
        throw new Error("Invalid track data: Each track must have a string title, string artist ,a numeric year and must not be empty.");      }
  
      if (!result[track.year]) {
        result[track.year] = [];
      }
  
      result[track.year].push(track.title);
    }
  
    // Sort titles alphabetically for each year
    for (const year in result) {
      result[year].sort();
    }
  
    return result;
  }
  
  // Predefined input
  const tracks = [
    { title: 'Blinding Lights', artist: 'The Weeknd', year: 2020 },
    { title: 'Levitating', artist: 'Dua Lipa', year: 2021 },
    { title: 'Save Your Tears', artist: 'The Weeknd', year: 2020 },
  ];
  
  try {
    console.log(getMusicTitlesByYear(tracks));
  } catch (error) {
    console.error(error.message);
  }
  
  /* Expected Output:
  {
    2020: ['Blinding Lights', 'Save Your Tears'],
    2021: ['Levitating']
  }
  */
  
  // Error Handling Test Cases
  try {
    console.log(getMusicTitlesByYear("invalid input"));
  } catch (error) {
    // console.error(error.message); // Expected: "Invalid input: Expected an array of music track objects."
  }
  
  try {
    console.log(getMusicTitlesByYear([{ title: "Song X", artist: "Artist X" }])); 
  } catch (error) {
    // console.error(error.message); // Expected: "Invalid track data: Each track must have a string title and a numeric year."
  }

  try {
    console.log(getMusicTitlesByYear([{artist: "Artist X" }])); 
  } catch (error) {
    // console.error(error.message); // Expected: "Invalid track data: Each track must have a string title and a numeric year."
  }

  try {
    console.log(getMusicTitlesByYear([]));  // No data case
  } catch (error) {
    // console.error(error.message); // Expected: "No data: The tracks array is empty."
  }