The keyboard (and its layout) is usually managed by some layer of your operating system software (or some utility started by the OS). It could depend upon your desktop environment.
On Linux, the keyboard layout is known to your display server (e.g. Xorg).
There is no direct connection with AngularJs. If you use that, some web browser is handling the keyboard layout (and the browser, e.g. firefox or chrome -not your application- would be aware of keyboard layout changes, and perhaps be notified by the display server or the window manager; for example look into X11 keymap-notify events that the Xorg server would send on Linux to the browser; on Windows see keyboard input functions and related in the WinAPI).
solved When i type in one field then its auto type another field