Source: models/keyboard.class.js

/**
 * Represents the state of specific keyboard keys.
 *
 * @class Keyboard
 */
class Keyboard {
    /**
     * Indicates if the left arrow key is pressed.
     * @type {boolean}
     */
    LEFT = false;
  
    /**
     * Indicates if the right arrow key is pressed.
     * @type {boolean}
     */
    RIGHT = false;
  
    /**
     * Indicates if the up arrow key is pressed.
     * @type {boolean}
     */
    UP = false;
  
    /**
     * Indicates if the down arrow key is pressed.
     * @type {boolean}
     */
    DOWN = false;
  
    /**
     * Indicates if the space bar is pressed.
     * @type {boolean}
     */
    SPACE = false;
  
    /**
     * Indicates if the "D" key is pressed.
     * @type {boolean}
     */
    D = false;
  }