Challenge: Double Rainbow

Challenge: Double Rainbow is a challenge in the Object-Oriented Design lesson. The goal is to use the object oriented technique to draw multiple rainbows.
== Challenge ==
This program describes a rainbow as an object literal and then draws it on the canvas. 
== Steps ==
There are three steps in this challenge:
# Create a Rainbow object that stores the x, y, and radius in a constructor function.
# Make a new variable to call the drawRainbow function, and draw the rainbow.
# Draw another rainbow in the same way with a different variable.
Category:Computing
Category:Intro to JS
Category:Object-Oriented Design
Category:Challenges