I am looking at doing an interactive plot where the X axis is the the month/day and the Y-axis is percentage from 0 - 100.

I want to be able to plot various data for various years. If the user clicks on a start date and end date, I want the code to know the dates so some type of action can be performed.

Does anyone know an API that can do this? Also, if it can be done on the web...that would be great too...