Creating Charts using data from doctype in Frappe

I am developing a simple Webapp using Frappe to store and display customer invoice payment information. In the first stage, I just want to display the data from a doctype using charts with the ability to filter by customer, invoice amount and date.
I have created a docType to store customer invoice payment information. It has following fields:
Customer [data]
Inv Number [data]
Inv Creation Date [date]
Inv Due Date [date]
Payment Date [date]
Invoice Amt [number]

I have also created a blank webpage. I am lost in how to query the doctype data (server side python) from javascript (client side) to create and display the graph. How should I go about this?