学习rails和AJAX。如何通过ajax加载div然后切换隐藏/显示它？

I'm doing my first Ruby on Rails project. I am working on a project where the user can add a new message. Then they can add updates to this message like a thread. I've got it all written and now I'm going back and applying some AJAX. I want to show just the main message when the page first loads. Then when I click a link I want an AJAX event to fire that populates a div with all the updates to the message. Then I want this same link to toggle hiding and showing the div.I'm doing my first Ruby on Rails project. I am