altKey property
bool
get
altKey
The MouseEvent.altKey
read-only property is a boolean value that
indicates whether the alt key was pressed or not when a given
mouse event occurs.
Be aware that the browser can't always detect the alt key on some operating systems. On some Linux variants, for example, a left mouse click combined with the alt key is used to move or resize windows.
Note: On Macintosh keyboards, this key is also known as the option key.
Implementation
external bool get altKey;