This script demonstrates how to get user availability information in Office 365 Exchange Online. You can get availability information for both multiple users and room mailboxes with this script.
Currently, Outlook Web App (OWA) allows you to check the availability information by using Schedule Assistant. But you still want to have a list of events to track the availability of meeting rooms.
You can find more All-In-One Script Framework script samples at https://aka.ms/onescriptingallery