src/lib/services/PhysicalKeyboard.js

/**
 * Physical Keyboard Service
 */
class PhysicalKeyboard {
  /**
   * Creates an instance of the PhysicalKeyboard service
   */
  constructor(simpleKeyboardInstance){
    /**
     * @type {object} A simple-keyboard instance
     */
    this.simpleKeyboardInstance = simpleKeyboardInstance;

    /**
     * Bindings
     */
    this.initKeyboardListener = this.initKeyboardListener.bind(this);
    this.getSimpleKeyboardLayoutKey = this.getSimpleKeyboardLayoutKey.bind(this);

    /**
     * Initialize key listeners
     */
    this.initKeyboardListener();
  }

  /**
   * Initializes key event listeners
   */
  initKeyboardListener(){
    // Adding button style on keydown
    document.addEventListener("keydown", (event) => {
      if(this.simpleKeyboardInstance.options.physicalKeyboardHighlight){
        let buttonPressed = this.getSimpleKeyboardLayoutKey(event);

        this.simpleKeyboardInstance.dispatch(instance => {
          let buttonDOM = instance.getButtonElement(buttonPressed) || instance.getButtonElement(`{${buttonPressed}}`);

          if(buttonDOM){
            buttonDOM.style.backgroundColor = this.simpleKeyboardInstance.options.physicalKeyboardHighlightBgColor || "#9ab4d0";
            buttonDOM.style.color = this.simpleKeyboardInstance.options.physicalKeyboardHighlightTextColor || "white";
          }
        });
      }
    });

    // Removing button style on keyup
    document.addEventListener("keyup", (event) => {
      if(this.simpleKeyboardInstance.options.physicalKeyboardHighlight){
        let buttonPressed = this.getSimpleKeyboardLayoutKey(event);

        this.simpleKeyboardInstance.dispatch(instance => {
          let buttonDOM = instance.getButtonElement(buttonPressed) || instance.getButtonElement(`{${buttonPressed}}`);

          if(buttonDOM && buttonDOM.removeAttribute){
            buttonDOM.removeAttribute("style");
          }
        });
      }
    });
  }

  /**
   * Transforms a KeyboardEvent's "key.code" string into a simple-keyboard layout format
   * @param  {object} event The KeyboardEvent
   */
  getSimpleKeyboardLayoutKey(event){
    let output;

    if(
      event.code.includes("Numpad") ||
      event.code.includes("Shift") ||
      event.code.includes("Space") ||
      event.code.includes("Backspace") ||
      event.code.includes("Control") ||
      event.code.includes("Alt") ||
      event.code.includes("Meta")
    ){
      output = event.code;
    } else {
      output = event.key;
    }

    /**
     * If button is not uppercase, casting to lowercase
     */
    if (
      output !== output.toUpperCase() ||
      (event.code[0] === "F" && Number.isInteger(Number(event.code[1])) && event.code.length <= 3)
    ) {
      output = output.toLowerCase();
    }

    return output;
  }
}

export default PhysicalKeyboard;