Keyboard Input design

When implementing the input system, we made compatibility for all inputs, this keyboard event can be implemented very simply. Input system design

API Design

/**
 * Input Manager.
 */
export class InputManager {

   /**
   * Whether the key is being held down, if there is no parameter, return whether any key is being held down.
   * @param key - The keys of the keyboard
   * @returns Whether the key is being held down.
   */
   isKeyHeldDown(key?: Keys): boolean {}
  
   /**
   * Whether the key starts to be pressed down during the current frame, if there is no parameter, return whether any key starts to be pressed down during the current frame.
   * @param key - The keys of the keyboard
   * @returns Whether the key starts to be pressed down during the current frame.
   */
   isKeyDown(key?: Keys): boolean {}

   /**
   * Whether the key is released during the current frame, if there is no parameter, return whether any key released during the current frame.
   * @param key - The keys of the keyboard
   * @returns Whether the key is released during the current frame.
   */
   isKeyUp(key?: Keys): boolean {}
}

/**
 * The keys of the keyboard.
 * Keep up with W3C standards.(https://www.w3.org/TR/2017/CR-uievents-code-20170601/)
 */
export enum Keys {
     //...
}