Like execute() but in the context of window {id}. The window will temporarily be made the current window, without triggering autocommands or changing directory. When executing {command} autocommands will be triggered, this may have unexpected side effects. Use :noautocmd if needed. Example:

call win_execute(winid, 'set syntax=python')

Doing the same with setwinvar() would not trigger autocommands and not actually show syntax highlighting.

Not all commands are allowed in popup windows. When window {id} does not exist then no error is given and an empty string is returned.

Can also be used as a method, the base is passed as the second argument:

GetCommand()->win_execute(winid)