Hey! Are you ready for a real hard check of your JavaScript skills, ninja? If you are still here, let's do it.

In this task, you need to implement the 2048 game like in this reference Don't play for too long! We need you to write the code!

Okay, what do we have?

1. HTML and CSS are already written. You can use it, or implement your own design if you want.
2. Base Game class structure is already written too. Extend it with your own methods. Obligatory methods (used in tests):

• constructor with initialState parameter (value is optional, defaults to the empty board)
• getState()
• getScore()
• getStatus()
• moveLeft()
• moveRight()
• moveUp()
• moveDown()
• start()
• restart()

3. Reference.

That's it!

Okay, okay. Also, we have some rules:

1. The game field is 4 x 4
2. Each cell can be empty or contain one of the numbers: 2, 4, 8 ... 2^n
3. The player can move cells with keyboard arrows
4. All the numbers should be moved in the selected direction until all empty cells are filled in
   • 2 equal cells should be merged into a doubled number
   • The merged cell can’t be merged twice during one move
5. The move is possible if at least one cell is changed after the move
6. After move 2 or 4 appears in a random empty cell. 4 probability is 10%
7. When 2048 value is displayed in any cell, win message should be shown.
8. The game over message should be shown if there are no more available moves.
9. Hide start message when game starts.
10. Change the Start button to Restart after the first move.
11. Restart button should reset the game to the initial state.
12. Increase score with each move. The score should be increased by the sum of all merged cells.
13. The game consists of 2 main parts:

• game logic written in src/modules/Game.class.js module that exports Game class
• game UI written in src/index.html with main.js script that need to use Game class instance

Hints:

• You have class field-cell--%cell_value%, for styling cell in the game.
• Use hidden class for hiding elements on page.
• Use start, restart classes for the main button for different styles.
• Use field-cell--%cell_value% class like additional class, don't replace the main class.
• Use keydown event and event.key property to handle arrow buttons presses

  document.addEventListener('keydown', event => console.log(event.key));

• Adding animation to the game is optional. It is a bit tricky, but you can try it if you want. Probably, you will need to extend the Game class with additional methods and create a separate board storage with Tile entities to operate their corresponding DOM elements' positions.

You can change the HTML/CSS layout if you need it.

1. Replace <your_account> with your Github username in the link
   • DEMO LINK
2. Follow this instructions
   • Run npm run test command to test your code;
   • Run npm run test:only -- -n to run fast test ignoring linter;
   • Run npm run test:only -- -l to run fast test with additional info in console ignoring linter.