Before the typhoon
Close every window and lock the latches.
Check hinges and rivets for looseness or rust.
Remove flowerpots and loose items from sills and balconies.
Draw the curtains to reduce flying glass if a pane breaks.
After the typhoon
Check whether any sash is loose, bent or won't close.
If anything is damaged, keep that sash shut and have a member firm inspect it promptly.
Official sources
This page is general guidance, not legal advice. If rules change, the government department's information prevails.