Suppose you have a region of a page where anyone can post a "pin" to it...
Like a browser-based version of a pinboard (or thumbtack board, however you call it...)
What js functions would you need to
1. dynamically detect the coordinates of the region clicked
2. update the region with a pin accordingly
I'll take mine raw
Here's a demo that is somewhat similar: TargetMap Demo. And I have other demos which might be helpful for that kind of app.