Objects are created in the code using object constructors.
Each object appears when its checkbox is clicked and disappears when its checkbox is unclicked.
Objects are redrawn when the user changes their attributes. (You can choose for this to happen immediately or after a Modify button is clicked.)
Adding, modifying, or removing an object does not affect the other objects.
Clicking a Save button outputs all of the data as an array of objects in JSON format. (It is fine if the output goes to the screen instead of being saved on the server.)