tool for visualizing simple 2d shapes

I'm drawing simple 2D line shapes using coordinate sets (for example, moveTo(x,y) drawTo(x,y)). I would like a tool that is like a sheet of graph paper. When I click on intersection points it records the coordinates I clicked and prints them to a dialog box.

Hopefully it would be a simple website in javascript or something. Does such a thing exist?

• This is kind of a which tech to use question. There really isn't a single correct answer to the question. – MichaelHouse Jun 29 '13 at 6:57