Is there any file/class holding constants for each keyboard events?

I think you want

if (event.key === KeyEventEnum.Enter) {
   ...
}

or

if (event.key === KeyEventEnum.Escape) {
   ...
}

or

if (event.key === KeyEventEnum.Shift) {
   ...
}

or

if (event.key === KeyEventEnum.Ctrl) {
   ...
}

instead of you are using like

if (event.key === "Enter") {
...
}

Angular doesn't have any constant or enum to hold all key code in one place but if you want any enum or constant then you please visit once to below link might be it help you. Its a angular package that you have to include it in your project.

https://github.com/nfriend/ts-keycode-enum

Use event.key instead of event.keyCode, keyCode returns 13 for enter and event.key returns "Enter" string

 HostListener('window:keyup', ['$event'])
    onKeyUp(event: KeyboardEvent) {
      if (event.key === "Enter") {
        this.onEnterClicked(event);
      }
    }